2001-6848 G ENGINEERING SERVICES DEPARTMENT
Capital Improvement Projects
city Of District Support Services
Encinitas F ield Operations
Sand Replenishment/Stormwater Compliance
Subdivision Engineering
Traffic Engineering
February 13, 2003
Attn: Insurance Company of the West
I.C.W. Park
P.O. Box 81063
San Diego, California 92138
RE: R.J. Daum Construction Company (Pacific Bell)
Grading Permit 6848 -G
APN 258- 140 -45
Final release of security
Permit 6848 -G authorized earthwork, storm drainage, and erosion control, all needed to
build the described project. The Field Operations Division has approved the project.
Therefore, final release of the security deposit is merited.
Performance Bond 1840673, in the amount of $75,209.00, is hereby fully exonerated.
The document original is enclosed.
Should you have any questions or concerns, please contact Debra Geishart at (760) 633-
2779 or in writing, attention this Department.
Sincerely, t �`
E
Masih Maher ay mbach
Senior Civil Engineer Finance Manager
Financial Services
Cc: Jay Lembach, FinanceManager
RJ Daum Construction Company
Debra Geishart
file
enc.
TEL 760 - 633 -2600 / FAX 760- 633 -2627 505 S. Vulcan Avenue, Encinitas, California 92024 -3633 TDD 760- 633 -2700 recycled paper
' STORM DRAIN REPORT
FOR
' PACBELL
ENCINITAS SITE 12
ENCINITAS, CALIFORNIA
' January 5, 2001
Prepared By:
' PARTNERS Planning and Engineering
9939 111bert Street, Suite 203
San Diego, CA 92131
(619) 695 -3344
' W.O. No.
' DWG No. -D
t
Andrew J. Kann., P. E., RCE 50940
Registration Expires 9 -30 -2001
C5
' TABLE OF CONTENTS
I. INTRODUCTION
A. Site and Project Description Page 1
B. Scope of work Page 1
C. Methodology and Assumptions Page 2
II. RESULTS AND CONCLUSIONS P age ;
LIST OF FIGURES
I. Figure 1: Vicinity Map Page 4
' CALCULATIONS
1. Hydrology Siunmary Page 5
' IL Hydraulic /lnlet Summary Page 6
' LIST OF APPENDICES
Appendix 1: Runoff Coefficients
Appendix 2: Time of Concentration Urban Areas Overland Time of Flow
Appendix 3: Watersheds 100 -Year 6 -Hour Precipitation
,Appendix 4: Watersheds 100 -Year 24 -1 Precipitation
Appendix 5: Intensity — Duration Design Chart
Appendix 6: 1landbook of Hydraulics Tables 7 -4 and 7 -14
' INTRODUCTION
Site and Project Description:
The site consists of approximately 0.95 acres of previously graded lot along Rosebay
Drive in Encinitas, see Figure No. 1 (page 4) for location. The site currently sheet flows
to on -site inlets and the runoff is conveyed to Rosebay via underground storm drain
system. The runoff is to be collected at the existing inlets and then conveyed to the
public storm drain system to the east of the project. The proposed development will
consist of an addition to the existing building. The runoff will be directed towards
various inlets which will then be conveyed to the existing storm drain system on -site. All
runoff will be discharged into an existing storm drain system.
' Scope of Work:
This drainage report has been prepared to document the design and calculation for the
drainage system associated with the site development of the Pacbell facility at Rosebay
Drive in Encinitas, California. See Location Map on Page 4.
1
� 1
' Hydrology /Hydraulics Methodology:
This drainage system has been designed in general conformance with the County of Sail
Diego Drainage Design Manual. Drainage basins are less than one square mile;
therefore, the Rational and Modified Rational Methods were utilized to calculate storm
runoff. The 100 -yr frequency storm has been used for runoff calculations.
1
• The following are the runoff coefficient used, see Appendix 1, Runoff Coefficients -
Undeveloped /Developed Area.
- Industrial Sites 0.95
' • Time of Concentration was calculated using Urban Areas Overland Time of Flow
Curves, See Appendix 2. A minimum time of concentration used was five minutes.
' • 1 determined by Isopuvials Charts for 100 -yr 24 & 6 hour Precipitation, Sec
Appendix 3 and 4.
• Intensity was calculated using the Rainfall Intensity - Duration Frequency Curves for
County of San Diego, see Appendix 5.
• Pipe sizing and flow routing was calculated by using Manning's equation for channel
flow. Calculations for pipes flowing partially full Tables 7 -4 and 7 -14 from
I andbook of Hydraulics, by Ernest F. Brater and Horace Williams King was used,
' see Appendix 6.
1
1
� 2
' RESULTS AND CONCLUSIONS
' The underground storm system is designed to convey the 100 -yr storm event with in the
curb and gutter onsite and the underground pipes have been designed to convey the
100 -yr storm event.
The pre- developed and post - developed basins are of the basic same area and there is no
diversion of flow from one basin to another.
No riprap will be required for the modification of the on -site system because it connects
directly to the public system in place.
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RATIONAL METHOD RUNOFF COEFFICIENTS
' LA LL USE
CO�FFICIEtJ'1' C
Soil Grout,
' Residential: B C D
Single Family .40 .45 .50 .55
' Multi -units 45 5o 60 70
Mobile homes .45 .50 .55 .65
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' .801 impervious
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' AS
HANDBOOK OF HYDRAULICS
' for ate Solution of
Hydraulic Engineering Problems
' Sixth Edition
Table 7 -19. Values of K' for Circular Channels in the Formula
' Q - K dlS
n
D - depth of water d - diumuter of channel
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.00 .01 .02 .03 .04 .05 .06 .07 .08 .09
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.9 .4J4 .406 .497 .498 .498 .408 .496 .4J4 .489 .483
1.0 ,463
iTEADY UNIFORM FLOW IN OPEN CIIANNEL; 7 -.i•i
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Circular Conduit Flowing Part Full
Let lepth n! -.racer - D
diam of chanmrl d end C. - the tabulated) Value. Then a - 4'.d'.
-
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d .00 .01 .02 .03 .04 ( .05 .06 .07 .03 .0
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' Section of a Circular Conduit Flowing Part Full
Let depth of venter _ D and the tabulated value. Then r - C, i.
disme�er of channel
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.171 .176 .130 .195 .199 i .193 .198 .202 .206 .210
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' REPORT OF GEOTECHNICAL INVESTIGATION
' PROPOSED PACIFIC BELL BUILDING ADDITION
137 RoSEBAY DRIVE
ENCINITAS, CALIFORNIA
Prepared for:
' ALLIED DESIGN GROUP - JWDA
San Diego, California
' April 28, 2000
LAWCRANDALL Project 70341 -0 -0060
p er ** _ -_�. _ _e pp
April 28, 2000
' Mr. Dennis F. Seguban
Allied Design Group - JWDA
' 2359 Fourth Avenue, Suite 300
San Diego, California 92101 -1606
' Subject: Report of Geotechnical Investigation
Proposed Pacific Bell Building Addition
137 Rosebay Drive
Encinitas, California
LAWCRANDALL Project 70341 -0 -0060
Dear Mr. Seguban:
L AWCRANDALL (LAW) is pleased to submit our report of geotechnical investigation of the site of
the subject project. This investigation was conducted in accordance with our proposal dated
' April 5, 2000, as authorized by your firm on April 7, 2000.
This report presents the results of our evaluation of the physical characteristics of the soil at the
' site of the proposed addition. Also included are our recommendations for design of foundations,
for floor slab support, and for earthwork. The results of the geotechnical field explorations and
laboratory tests as well as our limited geologic- seismic hazard evaluation are also presented.
' It has been a pleasure to be of professional service to you on this project and we look forward to
continuing our working relationship. Please call us if you have any questions regarding this
' report, or if we can be of further service to you on this or future projects.
Sincerely,
��R
LAWCRANDALL ,E D G�p�
' A Division of Law Engineer' ironmental Services, Inc ��c; F. R�OV,
c� ND. 1191
C9Y t� yu.— r CERTIFIED T .
ENGIP'EERING
OG
B a stal, P.E. NO. C M ry F. Rzonca, C.E.G. (p ' GEOL ° � IST �Q
Project Engmeer - * Senior Engineering Geologist 9p� UQ`�
q
OF CA
Nicholas G. Schmitt, P. . (KY)
Principal Engineer
g: IenglprjUWDAl0- 00321P- 011RptlPacific Bell Encinitas Report
(3 copies submitted)
Law /Crandall, A Division of Law Engineering and Environmental Services, Inc.
9177 Sky Park Court, Suite A San Diego, CA 92123
' 853- 273 -3600 o Far. 858 -278 -5300
' Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWCIUNDALL Project 70311 -0 -0060
' Report of Geotechnical Investigation
TABLE OF CONTENTS
' SECTION PAGE
' 1.0 SCOPE ...................................................................................................... ............................... 1
2.0 PROJECT INFORMATION ..................................................................... ............................... 2
' 2.1 PROJECT DESCRIPTION .................................................................... ............................... 2
2.2 SITE CONDITION .............................................................................. ............................... 2
' 3.0 FIELD EXPLORATIONS AND LABORATORY TESTS ...................... ............................... 3
3.1 FIELD EXPLORATIONS ........................................................................ ............................... 3
3.2 LABORATORY TESTS .......................................................................... ............................... 3
4.0 SUBSURFACE CONDITIONS ................................................................ ............................... 4
5.0 LIMITED GEOLOGIC - SEISMIC EVALUATION ................................. ............................... 5
' 5.1 GEOLOGIC SETTING ......................................................................... ............................... 5
5.2 GEOLOGIC HAZARDS ....................................................................... ............................... 5
5.3 CONCLUSIONS ................................................................................... ..............................
6.0 RECOMMENDATIONS .......................................................................... ............................... 9
6.1 FOUNDATIONS ................................................................................ ............................... 9
6.2 SITE COEFFICIENT AND SEISMIC ZONATION ................................. ............................... 10
WALLSBELOW GRADE ........................................................................... ............................... 1 1
6.4 FLOOR SLAB SUPPORT ................................................................... ............................... 12
6.5 EARTHWORK .................................................................................... .............................
' 6.6 SHORING ........................................................................................ ............................... 15
6.7 GEOTECHNICAL OBSERVATION ..................................................... ............................... 16
' 7.0 BASIS FOR RECOMMENDATIONS ................................................... ............................... 18
8.0 BIBLIOGRAPHY ................................................................................... ............................... 19
LIST OF FIGURES
' 1 Plot Plan
2 Geologic Map
' 3 Regional Faults /Seismicity
APPENDICES
APPENDIX: FIELD EXPLORATIONS AND LABORATORY TESTING
1
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAR'CRAND.41.L Project 70341 -0 -0060
Report of Geotechnical Investigation
1.0 SCOPE
This report presents the results of our geotechnical investigation performed for the proposed
Pacific Bell building addition in Encinitas, California. The locations of the proposed addition and
our explorations are shown in Figure 1, Plot Plan. The purpose of our geotechnical investigation
was to identify the geotechnical conditions and geologic hazards at the site and to provide
recommendations for the design of foundations, for floor slab support, and for earthwork.
Our geotechnical investigation consisted of the following tasks:
- A limited geologic- seismic hazards evaluation to identify the geologic conditions beneath
the site and geologic hazards that may affect the project.
- A foundation investigation to determine the physical properties of the soils beneath the site
and to provide recommendations for the design of foundations, for floor slab support, and
for earthwork.
Studies to assess environmental hazards that may affect the site were beyond the scope of this
investigation.
Our recommendations are based on the results of our field explorations and laboratory tests,
geologic studies, and appropriate engineering analyses. The results of the field explorations and
laboratory tests are presented in the Appendix.
Our professional services have been performed using that degree of care and skill ordinarily
exercised, under similar circumstances, by reputable geotechnical consultants practicing in this or
similar localities. No other warranty, expressed or implied, is made as to the professional advice
included in this report. This report has been prepared for Allied Design Group - JWDA and their
design consultants to be used solely in the design of the proposed development. The report has not
been prepared for use by other parties, and may not contain sufficient information for purposes of
other parties or other uses.
1
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWCRANDALL Project 1 - 0311 -0 -0060
Report of Geotechnical Investigation
2.0 PROJECT INFORMATION
2.1 PROJECT DESCRIPTION
the proposed addition will consist of constructing a one-story building
We understand that p p S ry g
addition over a subterranean basement level adjacent to the eastside to the existing Pacific Bell
building. The building addition will approximately 8,700 square feet in plan and will be
constructed of reinforced concrete and masonry units. Design loading information was not
provided but is anticipated to be light to moderate, maximum column loads of less than 120 kips
and maximum wall loads of less than 3.5 kips per linear foot. The finish floor elevation of the
basement level will be established at approximately Elevation 90 feet above Mean Sea Level
(msl). The earthwork will primarily consist of excavations for the basement level, minor site
grading, and excavation and backfilling of utility trenches.
2.2 SITE CONDITION
The site of the proposed building addition is adjacent to the existing Pacific Bell facility at 137
Rosebay Drive in Encinitas, California. The site is relatively flat and currently used for surface
parking. Existing grades range between approximate Elevation 99 msl to Elevation 103 msl and
slope toward the existing structure.
2
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA L.4WCR.4ND.4LL Project 70341 -0 -0060
' Report of Geotechnical Investigation
3.0 FIELD EXPLORATIONS AND LABORATORY TESTS
3.1 FIELD EXPLORATIONS
and groundwater conditions beneath the site of the proposed building The soil g P P g addition were
explored by drilling three borings to depths of 21 feet below the existing grade using
8 -inch diameter hollow -stem auger drilling equipment at the locations shown on Figure 1. Details
of the explorations and the logs of the borings are presented in the Appendix.
3.2 LABORATORY TESTS
Laboratory tests were performed on selected samples obtained from the borings to aid in the
classification of the soils and to determine the pertinent engineering properties of the foundation
soils. The following tests were performed:
Moisture content and dry density determinations.
Direct shear tests.
All testing was done in general accordance with applicable ASTM specifications. Details of the
laboratory testing program and test results are also presented in the Appendix.
3
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWCPUNDALL Project "0341 -0 -0060
Report of Geotechnical Investigation
4.0 SUBSURFACE CONDITIONS
Topsoil up to 1.5 feet thick were encountered in one of our three borings. The topsoil consists of
loose, very fine to fine sand. Alluvial /colluvial soils were encountered in all three of our borings.
The alluvial /colluvial soils consist of medium dense to dense, fine to medium sand.
Beneath the alluvial /colluvial soils, the site is underlain by bedrock of the Tertiary age Torrey
Sandstone. Where encountered in our exploratory borings, the Torrey Sandstone consists of fine- to
coarse - grained sandstone with trace amounts of fine gravel. The bedrock was moderately to highly
weathered and typically weakly cemented.
Groundwater or water seepage was not encountered in our exploratory borings.
w
4
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWC29NDALL Project 70341 -0 -0060
Report of Geotechnical Investigation
5.0 LIMITED GEOLOGIC - SEISMIC EVALUATION
5.1 GEOLOGIC SETTING
The site is located within the Coastal Plain of the Peninsular Ranges geomorphic province in
western San Diego County. The dominant structural trend of the Peninsular Range is defined by
faults associated with the Rose Canyon and Elsinore fault zones, along with other similar northerly
and northwesterly- trending fault zones in southern and Baja California. The coastal plain is a
narrow strip, 5 to 10 miles wide, consisting of Pleistocene age marine terrace deposits. These
were developed and preserved as a result of seaward regression and regional uplift since early
Pleistocene time (Eisenberg, 1985). Subsequent erosion has created a mesa -like topography
exposing the older Tertiary age units in the vicinity of the site. The eastern margin of the coastal
plain is the contact between the Tertiary sedimentary rocks and the underlying Southern California
Batholith, which is exposed to the east.
The areal geology in the vicinity of the site is depicted on Figure 2, Local Geology. The site is
shown in relation to major fault zones and earthquake epicenters on Figure 3, Regional Faults and
Seismicity.
5.2 GEOLOGIC HAZARDS
Faults
The numerous faults in Southern California include active, potentially active, and inactive faults.
The definition of fault terms used in this report are based on those developed for the Alquist - Priolo
Special Studies Zones Act of 1972, by the California Division of Mines and Geology (Hart, 1994).
Active faults are defined as those that have had surface displacement within Holocene time
(approximately the last 11,000 years) and /or have been included within an Alquist- Priolo Special
Studies Zone. Faults are considered potentially active if they show evidence of surface
displacement since the beginning of Quaternary time (about two million years ago) but not since
the beginning of Holocene time. Inactive faults are those that have not had surface movement
since the beginning of Quaternary time.
5
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWCRMDAtl Project %0341 -0 -0060
Report of Geotechnical Investigation
The site is not within a current Alquist- Priolo Special Studies Zone for fault surface rupture
hazard. No active or potentially active faults are known to pass directly beneath or project towards
the site. Therefore, the potential for surface rupture due to faulting occurring beneath the site
' during the design life of the proposed structure is considered low.
Active Faults
The closest known active faults to the site are within the Rose Canyon Fault Zone (RCFZ). This
fault zone comes onshore in La Jolla Bay and extends south - southeast through Rose Canyon along
the inland edge of Mission Bay to downtown San Diego. The closest mapped trace of the fault
zone is offshore located about 5.0 miles (8.0 kilometers) west- southwest of the site. Known major
active faults (some within the RCFZ) or fault zones that could cause significant ground shaking at
the site include the: Newport- Inglewood Fault Zone located 9.0 miles (14.4 kilometers) northwest;
Coronado Bank fault located 19.2 miles (31 kilometers) southwest; Spanish Bight fault located
21.6 miles (35 kilometers) south - southeast; Coronado fault located 24 miles (39 kilometers) south -
southeast; Silver Strand fault located 25.2 miles (41 kilometers) south - southeast; Elsinore fault
located 26.4 miles (43 kilometers) northeast of the site; San Diego Trough fault located 29.4 miles
(47 kilometers) southwest; San Miguel - Vallecitos fault located 37.8 miles (61 kilometers) south -
southeast; San Jacinto Fault Zone located 51 miles (82 kilometers) northeast; and Imperial fault
located 101 miles (163 kilometers) east - southeast of the site. The active San Andreas Fault, which
is generally considered the most significant fault in California, is located 76 miles (97 kilometers)
northeast of the site.
Potentially Active Faults
The closest major potentially active fault to the site is an unnamed fault that crosses Encinitas
Boulevard at Rosebay Drive and is projected to run along the western edge of the existing Pacific
' Bell facility (Eisenberg, 1985). This fault cuts through and displaces Tertiary age Torrey
Sandstone, and may offset Pleistocene age marine terrace deposits as well, but is not known to
displace younger sediments. Other, nearby, potentially active faults include the La Costa Ave fault
located 2.8 miles (4.5 kilometers) north - northwest, Christianitos fault located 27.6 miles (44.5
kilometers) north - northwest, Carmel Valley fault located 10.8 miles (17.4 kilometers) south, Point
Loma fault located 20.4 miles (33 kilometers) south, Florida Canyon fault located 21.0 miles (34
kilometers) south - southeast, Texas Street fault located 21.2 miles (34.2 kilometers) south -
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southeast, La Nacion fault zone located approximately 21.8 miles (35 kilometers) south - southeast,
and Fort Rosecrans fault located 21.0 miles (34 kilometers) south - southeast of the site.
Seismicity
The site is located in northwestern San Diego County, an area of low seismicity compared to the
general Southern California area, which has high seismic activity considered as a whole.
Historically (approximately the last 200 years), only one large- magnitude earthquake has occurred
in the immediate metropolitan San Diego area. However, the San Diego area has been subject to
ground shaking on many other occasions as a result of earthquakes in the surrounding, more
highly seismic Southern California/Northern Baja California and offshore regions. Locations of
significant faults, and epicenters of major earthquakes (magnitude greater than 6.0) in the
surrounding area, are shown on Figure 3, Regional Faults and Seismicity.
The site could be subjected to strong ground motion in the event of an earthquake. However, this
hazard is common in Southern California and the effects of ground shaking can be mitigated if the
proposed development is designed and constructed in conformance with current building codes
and engineering practices.
Liquefaction and Seismically- Induced Settlement
Liquefaction potential is greatest where the ground water level is shallow, and loose, fine sands
occur within a depth of about 50 feet or less. Groundwater was not encountered in our exploratory
borings to a depth of 20 feet below the ground surface. Furthermore, dense sands of the Torrey
Sandstone lie at approximately 10 feet below the ground surface. Due to the shallow proximity of
consolidated bedrock and lack of ground water, the potential for liquefaction and associated
ground deformation occurring beneath the site is considered remote and will not be an issue for the
planned project.
Subsidence
The site is not within an area of known subsidence associated with fluid withdrawal (groundwater or
petroleum), peat oxidation, or hydrocompaction.
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Landsliding and Lurching
The relatively flat -lying topography at the site precludes both slope stability problems and the
potential for lurching (earth movement at right angles to a cliff or steep slope during ground
shaking). There are no known landslides near the site, nor is the site in the path of any known or
potential landslides.
Tsunamis, Seiches, and Flooding
The site is located about 1.5 miles inland from the Pacific Ocean at an elevation of approximately
100 feet above sea level. Therefore, no risk of damage from seismic sea waves (tsunamis) is
anticipated.
The site is not located downslope or near large bodies of water that could adversely affect the site
in the event of earthquake- induced failures or seiches (wave oscillations in an enclosed or semi -
enclosed body of water).
5.3 CONCLUSIONS
Based on the available geologic data, no known active or potentially active faults with the
potential for surface fault rupture are known to exist directly beneath the site. Accordingly, the
potential for surface rupture at the site due to faulting is considered low during the design life of
the proposed building. Although the site could be subjected to strong ground shaking in the event
of an earthquake, this hazard is common in Southern California and the effects of ground shaking
can be mitigated if the building is designed and constructed in conformance with current building
codes and engineering practices.
The site is relatively level and the absence of nearby slopes precludes slope stability hazards. The
potential for other geologic hazards such as liquefaction, seismic settlement, subsidence, flooding,
tsunamis, inundation, and seiches affecting the site is considered low to remote.
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6.0 RECOMMENDATIONS
6.1 FOUNDATIONS
The proposed basement level of the building addition will extend into to the bedrock materials
encountered in our borings within the building plan. The building addition may be supported on
spread footings established in undisturbed bedrock materials.
Bearing Value
established in the undisturbed bedrock materials may be designed to impose a ootings y dead-plus
g p p
live load pressure of 5,000 pounds per square foot. All footings should be established at a depth
of at least 2 feet below the lowest adjacent grade or floor level, whichever is lower. Footing
excavations should be deepened as necessary to extend into satisfactory bearing materials.
A one -third increase in the bearing value can be used for wind or seismic loads. The
recommended bearing value is a net value, and the weight of concrete in the footings can be taken
as 50 pounds per cubic foot; the weight of soil backfill can be neglected when determining the
downward loads.
Settlement
Structural loads are not known at the time of this investigation. However, structural loads are
anticipated to be light to moderate and settlement of the proposed building addition supported on
spread footings as recommended, should be less than '/2 inch. Differential settlement should be
less than ' / 4 inch.
Lateral Loads
Lateral loads may be resisted by friction and by the passive resistance of the soils. A coefficient of
friction of 0.4 may be used between footings or the slab -on -grade floors for the underlying
materials. The passive resistance may be assumed to be equal to the pressure developed by a fluid
with a density of 300 pounds per cubic foot. A one -third increase in the passive value may be used
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for wind or seismic loads. The passive resistance of the materials may be combined with the
frictional resistance without reduction in determining the total lateral resistance.
Footing Observation
To verify the presence of satisfactory materials at design elevations, all footing excavations should
be observed by personnel of our firm. Footing excavations should be cleaned of any loosened soil
and debris before placing steel or concrete. Footing excavations should be observed and probed
for soft areas. Any soft, loose, or unsatisfactory materials should be removed and replaced with
lean concrete.
All applicable requirements of the California Construction and General Industry Safety Orders, the
Occupational Safety and Health Act of 1970, and the Construction Safety Act should be met.
Inspection of footing excavations may be required by the appropriate reviewing governmental
agencies. The contractor should be familiar with the inspection requirements of the reviewing
agencies.
6.2 SITE COEFFICIENT AND SEISMIC ZONATION
The site coefficient, S, can be determined as established in the Earthquake Regulations under
Section 1629 of the UBC, 1997 edition, for seismic design of the proposed building addition.
Based on a review of the local soil and geologic conditions, the site may be classified as Soil
Profile Type Sg, as specified in the 1997 code. The site is located within UBC Seismic Zone 4.
The site is near the Rose Canyon Fault Zone (RCFZ), which has been determined to be a Type B
seismic source by the California Division of Mines and Geology. According to Map 0 -36 in the
1998 publication from the International Conference of Building Officials entitled "Maps of
Known Active Fault Near - Source Zones in California and Adjacent Portions of Nevada," the
proposed building addition is located at a distance of 8.0 kilometers from the RCFZ. At this
distance for a seismic source type B, the near source factors, N and N,,, are to be taken as 1.00
and 1.08 respectively, based on Tables 16 -S and 16 -T of the 1997 UBC.
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WALLS BELOW GRADE
Walls below grade should be designed to resist a trapezoidal distribution of lateral earth pressure
plus any lateral surcharge from adjacent loads. The recommended pressure distribution for the
case where the grade is level behind the wall is illustrated below, with the maximum pressure
equal to 24H in pounds per square foot, where H is the height of the wall in feet.
0.2H
H= HEIGHT OF 0.6H
WALL IN FT.
0.2H
(P.S.F.)
The recommended earth pressure assumes that a drainage system will be installed the behind the
base of the basement walls, so that external water pressure will not develop against the basement
walls.
Drainage behind the basement walls may be provided by vertical strips of a geosynthetic drainage
composite. The strips may be placed at a depth starting at about 4 feet below the existing grade.
The strips should be at least 4 feet wide and placed 8 feet on centers. The drain should be
' continuous within the lower 4 feet of the wall. The drain should be connected to a 6- inch - diameter
perforated pipe surrounded by 6 inches of /4 -inch gravel or crushed rock surrounded by a filter
fabric. The perforated pipe should be connected to a drainage system through a solid pipe.
In addition to the recommended earth pressures, the upper 10 feet of walls adjacent to vehicular
traffic areas should be designed to resist a uniform lateral pressure of 100 pounds per square foot,
acting as a result of an assumed 300 pounds per square foot surcharge behind the walls due to
normal traffic. If the traffic is kept back at least 10 feet from the walls, the traffic surcharge may
be neglected.
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6.4 FLOOR SLAB SUPPORT
If the grading recommendations presented in this report are followed, the floor slabs of the
' proposed buildings may be supported on grade.
' Construction activities and exposure to the environment can cause deterioration of the prepared
subgrade. Therefore, we recommend that our field representative observe the condition of the
' final subgrade soils immediately prior to slab -on -grade construction, and, if necessary, perform
further density and moisture content tests to determine the suitability of the final prepared
' subgrade.
If vinyl or other moisture - sensitive floor covering is planned, we recommend that the floor slab in
' such areas be underlain by a capillary break consisting of a vapor- retarding membrane over a 4-
inch -thick layer of gravel. A 2- inch -thick layer of sand should be placed between the gravel and
' the membrane to decrease the possibility of damage to the membrane. We suggest the following
gradation for the gravel:
Sieve Size Percent Passing
' 3 /<" 90- 100
No.4 0-10
' No. 100 0- 3
' Low - slump. concrete should be used to minimize possible curling of the slab. A 2- inch -thick layer
of coarse sand can be placed over the vapor retarding membrane to reduce slab curling. If this
sand bedding is used, care should be taken during the placement of the concrete to prevent
displacement of the sand. The concrete slab should be allowed to cure properly before placing
vinyl or other moisture - sensitive floor covering.
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6.5 EARTHWORK
General
The earthwork will primarily consist of excavations for the basement level, minor site grading, and
the excavation and backfilling of utility trenches. All fill and backfill soils should be compacted
and as recommended in this report.
Excavation
The alluvial /colluvial and weathered formational soils, which extend to 10 feet below the existing
grade, are not expected to pose unusual excavation difficulties and conventional earthmoving
equipment may be used. Where there is not sufficient space for sloped embankments, shoring will
be required. Recommendations for shoring are presented in Section 6.7.
Temporary unsurcharged excavations may generally be made at 1:1 (horizontal to vertical). Some
sloughing of the surface soils should be anticipated. The excavations should be observed by our
firm so that any necessary modifications in slopes can be made based on variations in the soil
conditions encountered in the field.
The bottom of any unshored excavation should be restricted so as not to extend below a plane
inclined at 1' /z:l downward from the footings of adjacent existing structures unless shoring and/or
underpinning are provided.
Where sloped excavations are used, the tops of the slopes should be barricaded to prevent vehicles
and storage loads within 10 feet of the tops of excavated slopes. If the temporary construction
slopes are to be maintained during the rainy season, berms are recommended along the tops of the
slopes, to prevent runoff water from entering the excavation and eroding the slope faces. All
applicable requirements of the California Construction and General Industry Safety Orders, the
Occupational Safety and Health Act of 1970, and the Construction Safety Act should be met.
Subgrade Preparation and Moisture Conditioning
After the site is cleared and the excavations to the desired depth are performed, the exposed soils
should be carefully observed for the removal of all unsuitable deposits. Next, the exposed soils
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should be rolled with heavy compaction equipment. No scarification and compaction is required if
the exposed subgrade within a building pad consist entirely of clean undisturbed bedrock
materials.
Compaction
After observing and compacting the exposed subgrade soils, any required fill should be placed in
horizontal lifts not more than 8 inches in loose thickness and compacted to at least 90% of the
maximum dry density in accordance with ASTM D1557 -91. The moisture content of the fill
should be maintained at optimum or about 2% above optimum during compaction.
Material for Fill
The on -site soils, less any contaminated soil, debris or organic matter may be used in the required
site fills. Any rock or other soil fragments greater than 4 inches in size should not be used in the
required fills.
Any required imported fill should consist of relatively non- expansive soils with an Expansion
Index (ASTM D4829 -95) of less than 35. Import material should be approved by our firm prior to
arrival at the site and should contain sufficient fines (binder material) so as to provide a compacted
fill that will be relatively impermeable and will be stable in shallow trenches.
Backfill
All required structural and utility trench backfill should be mechanically compacted. Flooding
should not be permitted. The exterior grades should be sloped to drain away from the structures to
minimize ponding of water adjacent to the basement walls and foundations. Minimum site
gradients of at least 5% in the landscaped areas and of 1% in the hardscaped areas are
recommended in the areas surrounding buildings. Compaction of the backfill as recommended
herein will be necessary to reduce settlement of the backfill and associated settlement of the
overlying walks, paving, and utilities. All backfill below structures, slabs and pavements and
structural fill should be compacted to at least 90% (ASTM D1557 -91).
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6.6 SHORING
General
Where there is not sufficient space for sloped embankments, shoring will be required. Because the
planned excavations are anticipated to be on the order of 12 feet deep, cantilevered shoring should
be feasible. One method of shoring would consist of steel soldier piles placed in drilled holes and
backfilled with concrete.
The bottom elevations of the footings of the existing Pacific Bell building adjacent to the addition
are not known at this time. If the bottom elevations of the footings are within a plane drawn at 1:1
upward from the edge of any shored excavation, we should contacted for additional
recommendations.
The following information on the design and installation of the shoring is as complete as possible
at this time. We can furnish any additional required data as the design progresses. Also, we
suggest that our firm review the final shoring plans and specifications prior to bidding or
negotiating with a shoring contractor.
Lateral Pressures
For design of cantilevered shoring, a triangular distribution of lateral earth pressure may be used.
It may be assumed that the retained soils with a level surface behind the cantilevered shoring will
exert a lateral pressure equal to that developed by a fluid with a density of 30 pounds per cubic
foot. The use of cantilevered shoring adjacent to any existing structures should be carefully
evaluated since such shorings will be subject to deflection more than a braced or tied -back
shoring.
In addition to the recommended earth pressure, the upper 10 feet of shoring adjacent to areas with
regular vehicular traffic should be designed to resist a uniform lateral pressure of 100 pounds per
square foot behind the shoring due to normal street traffic. If the traffic is kept back at least 10
feet from the shoring, the traffic surcharge may be neglected.
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Design of Soldier Piles
For the design of soldier piles spaced at least two diameters on centers, the allowable lateral
bearing value (passive value) of the soils below the level of excavation may be assumed to be 800
pounds per square foot per foot of depth, up to a maximum of 6000 pounds per square foot. To
develop the full lateral value, provisions should be taken to assure firm contact between the soldier
piles and the undisturbed soils. The concrete placed in the soldier pile excavations may be a lean -
mix concrete. However, the concrete used in that portion of the soldier pile which is below the
excavated level should be of sufficient strength to adequately transfer the imposed planned exca g q Y loads p
to the surrounding soils.
Lagging
Continuous lagging will be required between the soldier piles in the fill soils. The lagging should
be installed as the excavation proceeds. If the clear spacing between soldier piles does not exceed
five feet, the lagging between soldier piles may be omitted within the bedrock. If the lagging is
omitted, a wire mesh fabric should be draped over the face of the shoring to reduce chances of
falling chunks of rock or soil.
The soldier piles should be designed for the full anticipated lateral pressure. However, the
pressure on the lagging will be less due to arching in the soils. We recommend that the lagging be
designed for the recommended earth pressure but limited to a maximum value of 400 pounds per
square foot. Some caving and running of the upper fill soils should be anticipated and it will be
necessary to carefully backfill portions of the lagging with on -site clean sand or sand - cement
slurry after installation.
6.7 GEOTECHNICAL OBSERVATION
The subgrade preparation and the compaction of all required fill should be observed and tested
during placement by a representative of our firm. This representative should perform at least the
following duties:
• Observe the clearing and grubbing operations for proper removal of all unsuitable materials
including existing on -site fill soils.
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Evaluate the suitability of on -site and import soils for fill placement; collect and submit soil
samples for required or recommended laboratory testing where necessary.
Observe the fill and backfill for uniformity during placement.
' 0 Test backfill for field density and compaction to determine the percentage of compaction
achieved during backfill placement.
Observe and probe foundation materials to confirm that suitable bearing materials are
present at the design foundation depths.
The governmental agencies having jurisdiction over the project should be notified prior to
commencement of grading so that the necessary grading permits can be obtained and arrangements
can be made for required inspection(s). The contractor should be familiar with the inspection
requirements of the reviewing agencies.
t
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7.0 BASIS FOR RECOMMENDATIONS
The recommendations provided in this report are based on our understanding of the described
' project information and on our interpretation of the data collected during the subsurface
exploration. We have made our recommendations based on experience with similar subsurface
conditions under similar loading conditions. The recommendations apply to the specific project
discussed in this report; therefore, the building loads, and any change in building, wall, or site
grades, should be provided to us so we may review our conclusions and recommendations and
make any necessary modifications.
The recommendations provided in this report are also based on the assumption that representatives
of our firm will perform the necessary geotechnical observations and testing during construction.
The field observation services are considered a continuation of the geotechnical investigation and
essential to verify that the actual soil conditions are as anticipated. This also provides for the
procedure whereby Pacific Bell and Allied Design Group - JWDA can be advised of unanticipated
or changed conditions that would require modifications of our original recommendations. In
addition, the presence of our representative at the site provides Pacific Bell and Allied Design
Group - JWDA with an independent professional opinion regarding the geotechnical - related
construction procedures. If another firm were retained for the geotechnical observation services,
our professional responsibility and liability would be limited to the extent that we would not be the
geotechnical engineer of record.
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8.0 BIBLIOGRAPHY
Agnew, D.C., 1979, "Tsunami History of San Diego," in Abbot, P.L., and Elliott, W.J., editors,
"Earthquakes and other Perils, San Diego Region" San Diego Association of Geologists,
p. 47 -60.
Alfors, J.T., Burnett, J.L., Gay, T.E., 1973, "Urban Geology: Master Plan for California."
California Division of Mines and Geology, Bulletin 198.
Anderson, John G., and Luco, J. Enrique, 1983, "Consequences of Slip Rate Constraints on
Earthquake Occurrence Relations," Bulletin of the Seismological Society of America, Vol. 73,
No. 2, p. 471 -496.
Anderson, J.G., Rockwell, T.K., and Agnew, D.C., 1989, "Past and Possible Future Earthquakes of
Significance to the San Diego Region," Earthquake Spectra, Vol. 5, No. 2, p 299 -333.
Applied Technology Council, ATC -40, Seismic Evaluation and Retrofit of Concrete Buildings,
developed under a contract with the California Seismic Safety Commission (published 1996,
combined volumes, 626 pages).
Artim, E.R., and Streiff, D., 1981, "Trenching the Rose Canyon Fault Zone, San Diego,
California," United States Geologic Survey Open File Report 81 -879.
Artim, E. R., and Pinckney, C. J., 1973, "La Nacion Fault System, San Diego, California ",
Geological Society ofAmerica, v. 84, no. 3, p. 1075 -1080.
ASTM, 1997, "Soil and Rock: American Society for Testing and Materials ", vol. 4.08
for ASTM test methods D -420 to D -4914, 153 standards, 1,026 pages; and vol.
4.09 for ASTM test methods D4943 to highest #, 161 standards, 1,036 pages.
Blake, T., 1998, "FRISKSP, A Computer Program for Probabilistic Estimation of Peak
Acceleration and Uniform Hazard Spectra Using 3 -D Faults as Earthquake Sources."
Bolt, B.A., 1973, "Duration of Strong Ground Motion," in Proceedings, Fifth World Conference on
Earthquake Engineering.
Boore, D. M., Joyner, W., and Fumal, T.E., 1997, "Equations For Estimating Horizontal Response
Spectra And Peak Acceleration Form Western North American Earthquakes — A Summary
Of Recent Work ", Seismological Research Letters, v. 68, no. 1, p. 128 -153.
Boore, D.M., Joyner, W.B., and Fumal, T.E., 1994, "Estimation of Response Spectra and Peak
Accelerations from Western North American Earthquakes: An Interim Report, Part 2,"
U.S. Geological Survey Open File Report 94 -127.
Boore, D.M., Joyner, W.B., and Fumal, T.E., 1993, "Estimation of Response Spectra and Peak
Accelerations from Western North American Earthquakes: An Interim Report,"
U.S. Geological Survey Open File Report 93 -509.
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California Code of Regulations, Title 24, 1998 "California Building Code," 3 volumes.
' California Division of Mines and Geology, 1986, "Guidelines to Geologic /Seismic Reports,"
CDMG Note 42.
California Division of Mines and Geology, 1986, "Guidelines for Preparing Engineering
Geologic," CDMG Note 44.
California Division of Mines and Geology, 1986, "Guidelines for the Review of Geologic /Seismic
Reports," CDMG Note 48.
California Division of Mines and Geology, 1986, "Guidelines for Evaluating the Hazard of Surface
Fault Rupture Review," CDMG Note 49.
California Division of Mines and Geology, 1990, "Planning Scenario for a Major Earthquake,
San Diego - Tijuana Metropolitan Area
California Division of Mines and Geology, 1996, "Probabilistic Seismic Hazard Assessment for the
State of California," Open File Report 96 -08.
California Division of Mines and Geology, 1997, "Guidelines for Evaluating and Mitigating Seismic
Hazards in California," Special Publication 117.
California Institute of Technology, Magnetic Tape Catalog of Earthquakes for Southern California,
1932 -1998.
California Mining and Geology Board, 1996, "Guidelines for Evaluating the Hazard of Surface Fault
Rupture," California Division of Mines and Geology, 5 pages.
Clarke, S.H., Greene, H.G., Kennedy, M.P., and Vedder, J.G., 1987, "Geologic Map of the Inner
Southern California Continental Margin," California Division of Mines and Geology Map
No. 1 A.
Dolan, J.F., et al, 1995, "Prospects for Larger or More Frequent Earthquakes in the Los Angeles
Metropolitan Region, California," Science, Volume 267, 199 -205 pp.
' Elliott, W.J., 1989, "Age of Landsliding - Implication for Recency of Fault Movement along the
La Nacion Fault near Dusk Drive, San Diego California," in Roquemore, G., Tanges, S., and
Wright, M., editors, 1989, "Proceedings of the Workshop on Seismic Risk in the San Diego
' Region: Special Focus on the Rose Canyon Fault System," Southern California Earthquake
Preparedness Project, Governor's Office of Emergency Services, p.33 -34.
Eisenberg, L. I., 1985, "Pleistocene Faults and Marine Terraces, North San Diego County" In:
P.A. Abbott, ed., On the Manner of Deposition of the Eocene Strata in North San Diego
County, San Diego Association of Geologist Guide Book.
' Federal Emergency Management Agency, 1989, Flood Insurance Rate Map, City of San Diego,
California," Community Panel No. 060295 0128 C.
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Franzen, S., Lew, M., and Elliott, P.J., 1998, "Multiple Investigation Methods for Fault Rupture
Hazard Evaluation," in Proceedings of the First International Conference on Site
Characterization, edited by Robertson, P.K. and Mayne, P.W.
Gastil, R.G., Kies, R., and Melius, D.J., 1979, "Active and Potentially Active Faults: San Diego
County and northernmost Baja California, in Abbot, P.L., and Elliott, W.J., editors, "Earthquakes
and other Perils, San Diego Region," San Diego Association of Geologists, p. 47 -60.
Greene, H.G., and Kennedy, M.P., 1987, "Geology of the Inner - Southern California Continental
Margin," California Division of Mines and Geology, California Continental Margin Geologic
Map Series, Area 1, scale 1:250,000.
Greensfelder, R.W., 1974, "Maximum Credible Rock Acceleration from Earthquakes in California,"
California Division of Mines and Geology Map Sheet 23. ,
Hart, E.W., 1973, revised 1994, Fault- Rupture Hazard Zones in California, Alquist- Priolo
Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps," California Division of
Mines and Geology Special Publication 42.
Hart, M.W., 1974, " Radiocarbon ages of alluvium overlying the La Nacion Fault, San Diego
California," Geologic Society of America Bulletin, v. 85, no 8, p. 1329 -1332.
Houston, J.R., and Garcia, A.W., 1974, "Type 16 Flood Insurance Study: Tsunami Predictions for
Pacific Coastal Communities," U.S. Army Engineer Waterways Experiment Station, Hydraulic
Laboratory.
International Conference of Building Officials (1998): Maps of Known Active Fault Near - Source
Zones in California and Adjacent Portions of Nevada, Whittier, California.
International Conference of Building Officials (1997): Uniform Building Code, Whittier,
California.
Jackson, D.D., et al., 1995, "Seismic Hazards in Southern California: Probable Earthquakes, 1994 to
2024, Seismological Society of America Bulletin, Volume 85, Number 2.
Jennings, C.W., 1994, "Fault Activity Map of California and Adjacent Areas with Locations and
Ages of Recent Volcanic Eruptions," California Division of Mines and Geology Map No. 6.
Kahle, J.E., 1988, "A Geomorphic analysis of the Rose Canyon, La Nacion, and Related Faults in
San Diego Area, California," California Division of Mines and Geology Fault Evaluation
Report 196.
Kennedy, M.P. and Peterson, G.L., 1975, "Geology of the San Diego Metropolitan Area,
California," California Division of Mines and Geology, Bulletin 200.
Kennedy, M.P., and Tan, S.S., Chapman, R.H., and Chase, G.W., 1975, "Character and Recency of
Faulting, San Diego Metropolitan Area, California," California Division of Mines and
Geology, Special Report 123.
21
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LANCRANDALL Project 703.11 -0 -0060
Report of Geotechnical Investigation
Kennedy, M.P., and Tan, S.S., 1977, "Geology of National City, Imperial Beach, and Otay Mesa
Quadrangle, Southern San Diego Metropolitan Area, California," California Division of Mines
and Geology, Map Sheet 29.
Kennedy, M.P., and Welday, E.E., 1980, "Recency and Character of Faulting Offshore
Metropolitan San Diego, California, San Diego Bay and Immediate Offshore Shelf, San Diego
County, California," California Division of Mines and Geology, Map Sheet 40.
Kennedy, M.P., and Welday, E.E., 1981, "Recency and Character of Faulting Offshore
Metropolitan San Diego, California, Point La Jolla to Mexico, San Diego County, California,"
California Division of Mines and Geology, Map Sheet 42.
Kennedy, M.P., Clark, S.H., Greene, H.G., and Legg, M.R., 1980 "Recency and Character of
Faulting Offshore Metropolitan San Diego, California," California Division of Mines and
Geology, Map Sheet 41.
Kern, J.P., 1983 "Earthquakes and Faults in San Diego," Pickle Press.
Kohler,
S.L. Miller R.V. 1983, " Mineral Land Classification: Aggregate Materials in the
Western San Diego County Production - Consumption Region," California Division of Mines
and Geology, Special Report 153.
Kuper, H.T., 1976, "Reconnaissance of the Marine Sedimentary Rocks of South Western
San Diego County," in Ferrand, G.T., editor, 1977, "Geology of Southwestern San Diego
County and Northwestern Baja California," San Diego Association of Geologists.
Kuper, H.T., 1989, "La Nacion Fault System - Interpretation from Stratigraphic and Depositional
Evidence," in Roquemore, G., Tanges, S., and Wright, M., editors, 1989, "Proceedings of the
Workshop on Seismic Risk in the San Diego Region: Special Focus on the Rose Canyon Fault
System," Southern California Earthquake Preparedness Project, Governor's Office of
Emergency Services, p.31 -32.
Lindvall, S.C., Rockwell, T.K., and Lindvall, C.E., 1989, "The Seismic Hazard of San Diego
Revised: New Evidence for Magnitude 6+ Holocene Earthquakes on the Rose Canyon Fault
Zone," in Roquemore, G., Tanges, S., and Wright, M., editors, 1989, "Proceedings of the
Workshop on Seismic Risk in the San Diego Region: Special Focus on the Rose Canyon Fault
System," Southern California Earthquake Preparedness Project, Governor's Office of
Emergency Services, p.71 -79.
Lindvall, S.C., Rockwell, T.K., and Lindvall, C.E., 1990, "The Seismic Hazard of San Diego
Revised: New Evidence for Magnitude 6+ Holocene Earthquakes on the Rose Canyon Fault
Zone," in Proceedings Volume of the 4th U.S. Conference on Earthquake Engineering, May
1990.
Leighton and Associates, update 1983, revisions through August 1995, "City of San Diego
Seismic Safety Study."
Leighton and Associates, 1993, "City of San Diego Seismic Safety Study."
22
r Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA L.awCRANDALL Project "0311 -0 -0060
Report of Geotechnica! Investigation
Mark, R.K., 1977, Application of Linear Statistical Models of Earthquake Magnitude Versus
Fault Length in Estimating Maximum Expectable Earthquakes," Geology, Vol. 5, pp. 464 -466.
Marshall, Monte, 1989, "Detailed Gravity Studies and the Tetectonics of the Rose Canyon - Point
' Loma - La Nacion Fault System, San Diego, California," in Roquemore, G., Tanges, S., and
Wright, M., editors, 1989, "Proceedings of the Workshop on Seismic Risk in the San Diego
Region: Special Focus on the Rose Canyon Fault System," Southern California Earthquake
' Preparedness Project, Governor's Office of Emergency Services, p.80 - 99.
Mualchin, L. and Jones, A.L., 1992, "Peak Acceleration From Maximum Credible Earthquakes in
California (Rock and Stiff -Soil Sites)," California Division of Mines and Geology Open -File
Report 92 -1.
' OSHPD (Office of Statewide Health Planning and Development), 1995, "Reconciliation Between
OSHPD Review and Seismic Hazards Mapping Approaches to Probabilistic Seismic Hazards
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' Petersen, M.D., Bryant, W.A., and Cramer, C.H., 1996, "California Fault Parameters," California
Division of Mines and Geology, Open -File Report 96 -08, downloaded from
www.conrv.ca.gov/dmg/shezp/fltindex.htmi.
' Poland, J.R., Garrett, A.A., and Sinnott, Allen, 1959, "Geology, Hydrology, and Chemical
Character of Groundwaters in the Torrance -Santa Monica Area, California," U.S. Geological
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Seismic Risk in the San Diego Region: Special Focus on the Rose Canyon Fault System,"
' Southern California Earthquake Preparedness Project, Governor's Office of Emergency
Services, 106 p.
' San Diego, City of, 1979, "Seismic Safety Element," Progress Guide and General Plan.
San Diego, City of, 1995, "Seismic Safety Study, Geologic Hazards and Faults," Map No. 17.
San Diego, County of, 1974, "Landslides," San Diego County Planning Department, Map No. 1,
Scale: 1 inch to 2 miles.
San Diego, County of, 1975, "Seismic Safety Element," General Plan.
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Ph.D. Thesis, Princeton University, Princeton, New Jersey, 216 pp.
23
Allied Design Group - JWDA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAIVOU DALL Project '03 1 -0 -0060
t Report of Geotechnical Investigation V
Slemmons, D.B., 1979, "Evaluation of Geomorphic Features of Active Faults For Engineering
Design and Siting Studies," Association of Engineering Geologists Short Course.
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' San Diego and Coronado," in Abbott, P.C., editor, "Geologic Studies in San Diego, San Diego
Association of Geologist Field Trips."
' Testing Engineers -San Diego, Dames & Moore, Woodward -Clyde Consultants, 1985 "Geologic
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of Mines and Geology.
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Mines and Geology Open File Report 93 -02.
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Rupture Length, Rupture Width, Rupture Area, and Surface Displacement," Bulletin of the
' Seismological Society of America, Volume 84, No. 4, pp. 974 -1002.
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' California Division of Mines and Geology County Report 3.
Wesnousky, S.G., 1986, "Earthquakes, Quaternary Faults and Seismic Hazard in California,"
' Journal of Geophysical Research, Vol. 91, No. B12, pp. 12,587- 12,631.
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' and Geologists Bulletin, Volume 7, Nos. 1 and 2, Pages 107 -121.
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Study for the City of San Diego," Project No. 72 -279
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Youd, T. Leslie and Idriss, Izzat M., 1997, Proceeding of the NCEER Workshop on Evaluation of
Liquefaction Resistance of Soils, National Center for Earthquake Engineering Research,
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Ziony, J.I., and Yerkes, R.F., 1985, "Evaluating Earthquake and Surface Faulting Potential," in
Ziony, J.1., ed., Evaluating Earthquake Hazards in the Los Angeles Region - An Earth Science
Perspective, U.S. Geological Survey Professional Paper 1360, p. 43 -91.
24
Allied Design Group - Jff'DA April 28, 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LaiUCR4. -voALL Project 7 0341 -0 -0060
Report of Geotechnical Investigation
r
FIGURES
■
JOB 70341 -0 -0060 DATE 00 DR FAA O.E. BEC CHKD.
o�
s
i
g
z
.E�B �Y
D IZIVE
aos
CL '
v
i
i
i
1
i
t
..t t
i
�1
1
i
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1
E
b
F
t 1
(
Q
r
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sZ
a �5
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SCALE: 1 " =30'
C)
D
Z
D
� r
c r
rn
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V ; � �: . ' �:, � � Gam �
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REFERENCE:
W EISENBERG, L.I., 1983 PLEISTOCENE MARINE TERRACE and EOCENE GEOLOGY, Encinitas and Rancho Santa Fe
O Quadrangles, San Diego County, California [M.S. Thesis]: San Diego, California, San Diego State University, 386p.
0
0
v
w LOCAL GEOLOGY
o SCALE 1 "= 24,000'
0
0 .5 1
o I I I
o KILOMETERS
o LEGEND
n
Qsn Nestor Marine Terrace Deposit ......... Contact (dashed where approx.
z Qsp Palomar Marine Terrace Deposit located, dotted where concealed)
U Qsm Magdalena Marine Terrace Deposit
W Qsq Quial Marine Terrace Deposit Fault (dashed where approx.
a n Qsb Bulrush Marine Deposit ..... located, dotted where concealed:
Qsc Clairemont Marine Terrace Deposit U, upthrown, D, downthrown)
Qst Tecolote Marine Terrace Deposit
Tt Torrey Sandstone (Tertiary) \< Strike and Dip of Bedding
LAW/ CRANDALL
FIGURE.: 2
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Allied Design Group - JIUDA
April 28. 2000
Proposed Pacific Bell Building Addition, Encinitas, CA LAWOUADALL Project - 0341 -0 -0061)
Report of Geotechnical Investigation
i 1
I'
I'
APPENDIX
FIELD EXPLORATIONS AND LABORATORY TESTS
i
I
i' Allied Design Group - J11 DA April 28. 2000
Proposed Pacific Bel! Building Addition, Encinitas, CA L.4110 n7tALL Project - 03.11 -0-0060
I ' Report ofGeotechnicalInvestigation
APPENDIX
I
FIELD EXPLORATIONS AND LABORATORY TESTS
FIELD EXPLORATIONS
The subsurface conditions beneath the site were explored by drilling three borings to depths ol' 21
feet below the existing grade using an 8 -inch diameter hollow -stem auger drilling equipment at the
I,1
locations presented on Figure 1. Groundwater or water seepage was not encountered.
Our field geologist logged the soils encountered, and obtained undisturbed and bulk samples for
laboratory inspection and testing. The borings were backfilled with the excavated materials. 'I 1, e
logs of the borings are presented in Figures A -1.1 through A -1.3; the depths at Nvhi, h relativey
undisturbed samples were obtained are indicated to the left of the boring logs. The key to the
boring logs is presented in Figure A -2.1. The relatively undisturbed samples were obtained using
t a "Crandall" sampler. The Crandall sampler is a brass -ring -lined tube with an inside diameter of
2 inches and an outside diameter of 3 inches. The number of blows required to drive the
Crandall sampler 12 inches is indicated on the boring logs. The hammer used for the Crandall
I' sampler weighed 140 pounds and a drop height of 30 inches was used. Tile soils are classified in
the accordance with the Unified Soil Classification System described in Figure A -2.2.
LABORATORY TESTS
The field moisture content and dry density of the soils encountered were evaluated by performing
tests on the undisturbed samples in accordance with ASTM D2216 -92. The results of the tests are
shown to the left of the boring logs.
Direct shear tests were performed on eight relatively undisturbed samples to estimate the stren;,th
of the soils. The tests were performed at after soaking to near - saturated moisture content and at
various surcharge pressures. The yield -point values determined from the direct shear tests are
presented in Figure A -3, Direct Shear Test Data.
y — F- U
0 cc z o N ° BORING 1
' j. w. N 0� ii
° a
W O O o vi — g DATE DRILLED: April 14, 2000
w o m -2 0.0 Q EQUIPMENT USED: 8 -inch diameter hollow -stem auger
ELEVATION: 102.5
0 SP TOPSOIL
SAND - very fine to fine, dark to medium brown,
�•; slightly moist
100 ALLUVIUM /COLLUVIUM
SAND - medium dense light to dark brown, dry
5.0 109 37 " `'
j v 5
U
•v 4.8 86 23 `• medium brown
I c ,'.
aD
2.0 92 17 - * ..: SP TORREY SANDSTONE
10 ° :• SAND - fine, weathered, yellowish brown
0 M
le �
U C
U 90
3.8 97 31 some fine Gravel, trace coarse Sand, moist
U L.
O rt]
U rn
m c 15 .•
3.3 100 30 1 increased fine Gravel
0 O
U 0?
N o 85 SP SAND - fine, unweathered, very dense, hard drilling
r 0 ? n 20
0 7 1 7.7 108 50
p - for
a�
CL m
0 -} NOTE: Boring terminated at 21 feet.
P No water encountered.
t
LL C r,
p
O H '1
O N
N p
N
N _0
d p n
U 17
U
W U
N C
•p m
N
m
O a] n
O r _.
O F-
d O
M Z
O
n
M
O
LOG OF BORING
LAW /CRANDAL ::
FIGUI E A -1.1
z z_ U
Z" o; ° BORING 2
w U y w cn -0 w p `� p a } v 3 o DATE DRILLED: April 14, 2000
w o m-0 0- Q EQUIPMENT USED: 8 -inch diameter hollow -stem auger
o v m to ELEVATION: 103
0 .. ", SP ALLUVIUM /COLLUVIUM
SAND - fine, dark brownish grey, moist
' 100
12.9 101 17 medium dense
5 t.
A
U
6.6 97 21 medium brown
95
d -
5.9 104 80 '
10 for Sp TORREY SANDSTONE
p o 10" SAND, fine, yellowish brown, very dense
Y vV
2 ('
L) c .E
� 90 14.7 97 50
U c for
O m 3"
U rn c
W •° 15
o 6.9 92 50 N light yellowish white
LL! .9 for
4 ,.
°• ° 85
` N
C' m
io 0 20
50
c
° o for
C d 5.,
CL
� L)
CL
CL fO
O c v
a °, � NOTE: Boring terminated at 21 feet.
�7 CD No water encountered.
LL C O
3 a l l
°
t
O y ,
O
0 E d,
N O
_ n;
d O w
U -0
N O
W U
Q w Z?
� j N
N C.
7
N `
_ m
O S
O O U
L
O N Vn
O r
O ~ Y
ci
� O
M Z
O
n
m
O
LOG OF BORING
LAW /CRANDALL
FIGURE A 1.2
F- ?• Z U
° _ Z" o ° BORING 3
�- �-
Q W. a U U J
w 0 00 N —° g DATE DRILL April 14, 2000
i� w g o tr -2 O - Q EQU USED: 8 -inch diameter hollow -stem auger
_ o m (n ELEVATION: 99
0 4" Asphalt Paving - 6" Aggregate Base
ALLUVIUM /COLLUVIUM
:'•' ; SP SAND - fine, dark brownish grey, moist
95 2.9 94 47 trace medium Gravel, dense
5
U `.t�•
v 9.2 110 16 1 ` = medium dense
C
� Y
a� 90
15 SP TORREY SANDSTONE
' m 10 SAND - fine, weathered, yellowish brown, medium dense
Y Ne v
M (D t
2 N
U c E r
O- 11.6 109 47 dense
' SP
o
85 very dense, unweathered
U I c
m 6 0 ° 15
.0 12.7 104 58 very dense, mottled yellowish brown with red
' W .9 6
o for
O .L m ,.
4) r
a o
� w
' a °' M
p � y 80
C
2 20
� c 6.8 98 50
o for
4
C ..
C L U
3 a `
a f0
C' 0
a NOTE: Boring terminated at 21 feet.
y No water encountered.
U_ C O
N
O
O N :�
O C (D
� C N
N O y
" a
N � y
C
' d o
U
N O
W U
Q U
N C
� C
7 m
N �
6 3
O o c 'o — c
O = N
O —
Q
M Z
O
n
CO
O
' LOG OF BORING
LAW /CRANDALL
1 FIGURE A -1.3
Crandall Sampler
No Recovery
Standard Penetration Sampler
® Bulk Sample
- #200 = % Passing No. 200 Sieve
LL = Atterberg Liquid Limit
PI = Atterberg Plasticity Index
ND = Not Detected
TV = Torvane
PP = Pocket Penetrometer
' Blow Count - Number of blows required to drive the Crandall or SPT sampler 12
inches using a 140 pound hammer falling 30 inches.
KEY TO BORINGS
LAW /CRANDALL L&
FIGURE A - 2.1
MAJOR DIVISIONS GROUP SYMBOLS TYPICAL NAMES
Well graded gravels, gravel - sand mixtures,
CLEAN GW little or no firm.
GRAVELS GRAVELS O°
Little or no fines ��
(Mare than 50% ( 1 �c� GP Poorly graded gravels or gravel -sand mixtures,
of coarse little or no firm.
fraction is
' LARGER than GRAVELS GM Silty gravels, gravel - sand - sift mixtures.
COARSE the 4 sieve WITH FINES
GRAINED size) (Appreciable
SOILS amok of Ones) GC Clayey gravels, gravel - sand - clay mixtures.
(More than 50%
of material is Wall graded sands, gravelly sands,
LARGER than CLEAN SW little or no fines.
No. 200 sieve SANDS SANDS
' sae) (More than 50% (Little or no fines) SP Poorly graded sands or gravelly sands,
of coarse little or no fines.
fraction is
' SMALLER than SANDS
the No. 4 sieve SM Silly sands, said - sift mixtures.
size) WITH FINES
(Appreciable
' amourt of fines) SC Clayey sands, sand - day mixtures.
ML Inorganic sifts and very fine sands, rock flour, silly or
clayey firm sands or clayey silts with slight plasticity.
SILTS AND CLAYS Inorganic clays of low to medium plasticity, gravely
FINE (mod limit LESS than 50) CL days, sandy clays, silly clays, lean clays.
' GRAINED
SOILS OL Organic sifts and organic silly clays of low plasticity.
(More than 50%
of material is Inorganic sifts, micaceous or diatomaceous
SMALLER than fine sandy or silty soils, elastic sifts.
No. 200 sieve
size) SILTS AND CLAYS
(Liquid limit GREATER than 50) CH Inorganic days of high plasticity, fat clays.
OH Organic days of medium to high plasticity,
organic sifts.
HIGHLY ORGANIC SOILS pt Peat and other highly organic soils.
BOUNDARY G 1 Soils possessing characteristics of two groups are desgnated by combinations of group symbols.
PARTICLE SIZE LIMITS
SILT OR CLAY SAND GRAVEL COBBLES WEIRS
Fine Medium Coarse Fine Coarse
No.200 No.40 No.10 No.4 3/4' T 12'
U. S. STANDARD SIEVE SIZE
UNIFIED SOIL CLASSIFICATION SYSTEM
Reference:
The Unified Soft Classification System, Corps of Engineers, U.S. Army
Technical Memorandum No. 3.357, Vol. 1 , March, 1953 (Revised April, 1960) LAW / C R A N D A L L
FIGURE A -2.2
SHEAR STRENGTH in Pounds per Square Foot
0 1000 2000 3000 4000 5000 6000
0
O
1 @6.5
1000 1 @9.5 e
O
0 t0 O 3 @9.5
U ` O 1 @12.5
iv
)
N
w m 2000
m a
V1
'O 1 @6.5
w c
O 0
CL
O
c
w 3000 BORING NUMBER &
m N SAMPLE DEPTH (FT.)
o OC
a
w
0 1 @9.5
Q 4000
V O @9.5
o �
S O 1 @12.5
N
5000
0
0
0
d
� 6000
0
KEY:
m ;
O
-' Samples tested after soaking to a moisture content near saturation
�--- Natural soils
Fill soils
DIRECT SHEAR TEST DATA
LAW /CRANDALL
FIGURE A - 3