HomeMy WebLinkAboutCDP 04-07; McGuire Residence; Coastal Development Permit (CDP) (3)ENGINEERING, INC.
CONSTRUCHON TESTING& ENGINEERING,INC.
SAN DIEGO, CA lUVERSIDE, CA
2414 Vineyard Ave. 490 E. Princeland Ct.
Suite G Suite 7
Escondido, CA 92029 Corona, CA 91719
(760)746-4955 (909) 371-1890
(760) 746-9806 FAX (909) 371-2168 FAX
VENTURA, CA TRACY, CA LANCASTER, CA SACRAMENTO, CA N. PALM SPRINGS, CA
1645 Pacific Ave. 242W.Larcli 42156 lOtli St. W. 3628 Madison Ave. 19020 N. Indian Ave.
Suite 105 Suite F Unitk Suite 22 Suite 2-K
Oxnard, CA 93033 Tracy, CA 95376 Lancaster, CA 93534 N. Higlllands, CA 95660 N. Palm Springs, CA 92258
(805)486-6475 (209)839-2890 (661)726-9676 (916)331-6030 (760)329-4677
(80S) 486-9016 FAX (209) 839-2895 FAX (661) 726-0246 FAX (916) 331-6037 FAX (760) 328-4896 FAX
RECEIVED
PRELIMINARY GEOTECHNICAL INVESTIGATION
PROPOSED IMPROVEMENTS TO MCGUIRE RESIDENCE MAR 1 0 2004
5035 TIERRA DEL ORO STREET CITY OF PAD I oo
CARLSBAD, CALIFORNIA p, . KiK,,):'f2
t^LANNlNG DEPT.
PREPARED FOR:
MR. JOHN PYJAR
DOMINY + ASSOCIATES ARCHITECTS
2150 WEST WASHINGTON, SUITE 303
SAN DIEGO, CALIFORNIA, 92110
PREPARED BY:
CONSTRUCTION TESTING & ENGINEERING, INC.
2414 VINEYARD AVENUE, SUITE G
ESCONDIDO, CALIFORNIA 92029
CTE JOBNO. 10-6766 MARCH 2, 2004
GEOTECHNICAL • ENVIRONMENTAL • CONSTRUCTION INSPECTION AND TESTING • CIVIL ENGINEERING • SURVEYING
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TABLE OF CONTENTS
Section Page
1.0 EXECUTIVE SUMMARY 1
2.0 INTRODUCTION AND SCOPE OF SERVICES 2
2.1 Introduction 2
2.2 Scope of Services 2
3.0 BACKGROUND INFORMATION 2
3.1 Site Location and Description 2
3.2 Proposed Improvements 3
4.0 FIELD AND LABORATORY INVESTIGATION 3
4.1 Field Investigations 3
4.2 Laboratory Investigation 4
5.0 GEOLOGY 4
5.1 General Physiographic Setting 4
5.2 Geologic Conditions 4
5.2.1 Fill Soils 5
5.2.2 Quatemary Terrace Deposits 5
5.3 Groundwater Conditions 5
5.4 Geologic Hazards 5
5.4.1 Local and Regional Faulting 6
5.4.2 Site Near Source Factors and Seismic Coefficients 6
5.4.3 Tsunami and Seiche Damage 7
5.4.4 Landsliding or Rocksliding 7
5.4.5 Compressible and Expansive Soils 7
5.4.6 Liquefaction Evaluation 8
5.4.7 Seismic Settlement Evaluation 8
5.4.8 Corrosive Soils 9
5.4.9 Bluff Erosion and Setbacks 9
6.0 CONCLUSIONS AND RECOMMENDATIONS 10
6.2.1 General 10
6.2.2 Site Excavations 11
6.2.3 Fill Placement and Compaction 11
6.2.4 Fill Materials 12
6.4.1 General 13
6.4.2 Spread Foundations and Slabs-on-Grade 14
6.4.3 Foundation Settlement 15
17
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6.10 Construction Observation 19
6.11 Plan Review 19
7.0 LIMITATIONS OF INVESTIGATION 19
FIGURES
FIGURE 1
FIGURE 2
INDEX MAP
EXPLORATION MAP
APPENDICES
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
REFERENCES CITED
EXPLORATION LOGS AND LIQUEFACTION
ANALYSIS
LABORATORY METHODS AND RESULTS
STANDARD SPECIFICATIONS FOR GRADING
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Proposed Improvements to McGuire Residence
5035 Tierra Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
1.0 EXECUTIVE SUMMARY
Our investigations were performed to provide site-specific geotechnical information for the
construction of the proposed improvements to the McGuire Residence on the west side of Tierta
Del Oro Street, in Carlsbad, Califomia. The proposed development is considered feasible from a
geotechnical viewpoint provided that recommendations in our report are implemented.
Based on our observations and reference review, soils beneath the site consist of fill soils
overlying Quatemary Terrace Deposits. Due to the different depths at which Quatemary Tertace
Deposits are found, there is approximately five feet of fill on the west side of the site and one
foot of fill on the east side of the site.
Groundwater was not encountered at this site during our investigation. During seasonal weather
changes, areas of local saturation may be encountered. However, fi-om a review of preliminary
project plans, we do not anticipate that groundwater will affect the proposed development,
provided appropriate surface drainage is maintained.
Based on the geologic findings and referenced review, no active surface faults are known to exist
at the site. In general, the results of our review indicate that the proposed project can be
constmcted as planned provided the recommendations presented in this report are followed.
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Proposed Improvements to McGuire Residence
5035 Tierta Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
2.0 INTRODUCTION AND SCOPE OF SERVICES
2.1 Introduction
Construction Testing and Engineering, Incorporated ("CTE") has prepared this geotechnical
engineering report for the proposed improvements to the McGuire Residence. The site is on the
west side of Tierra Del Oro Street, in Carlsbad, Califomia. Figure 1 is a map showing the
general location of the site.
2.2 Scope of Services
Our scope of services included:
• Review of readily available geologic reports pertinent to the site and adjacent areas
(Appendix A contains a list of cited references).
• Explorations to determine subsurface conditions to the depths influenced by the proposed
constmction.
• Laboratory testing of representative soil samples to provide data to evaluate the geotechnical
design characteristics ofthe site foundation soils.
• Definition of the general geology and evaluation of potential geologic hazards at the site.
• Preparation of this report detailing the investigation performed and providing conclusions
and geotechnical engineering recommendations for design and constmction.
3.0 BACKGROUND INFORMATION
3.1 Site Location and Description
The site is located on the west side of Tierra Del Oro Street approximately 0.5 mile west of
Interstate 5 Freeway. Figure 2 shows the approximate configuration of the site and existing
improvements.
The site is roughly rectangular in shape and slopes down slightly to the west. The site is situated
at an elevation of approximately 30 feet, overlooking the Pacific Ocean to the immediate west.
A moderate slope descends approximately 10 feet from the west limits ofthe building pad to a
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Proposed Improvements to McGuire Residence
5035 Tierra Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
nartow flat-lying area. An additional moderate slope descends approximately five feet to another
flat-lying area with riprap consisting of large boulders and beach and water line beyond. As
detailed further herein, the site and immediate vicinity do not appear to be significantly affected
by typical bluff erosion.
Land use near the site consists of residential properties. The north and south sides of the site are
bound by existing residences, the west side by the Pacific Ocean, and the east side by Tiena Del
Oro Street.
3.2 Proposed Improvements
We understand that the proposed development/project will include the demolition of most or all
existing improvements and the subsequent constmction of a new single story, wood frame
building and associated improvements. Associated improvements may include parking and drive
areas, utilities, and landscaping areas. We understand the proposed improvements will be
located in the same general area of the existing improvements and will cover the majority of the
site.
4.0 FIELD AND LABORATORY INVESTIGATION
4.1 Field Investigations
Field investigations at this site, performed Febmary 25, 2004, included site reconnaissance and
excavation of two soil borings. Soils were logged and visually classified in the field by a
geologist using the Unified Soil Classification System. The field descriptions have been
modified, where appropriate, to reflect laboratory test results. Excavation logs including
descriptions of the soil, in situ field-testing data, and supplementary laboratory data are included
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Proposed Improvements to McGuire Residence
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March 2, 2004 CTE Job No. 10-6766
in Appendix B. Figure 2 is a map showing the approximate locations of the explorations
conducted by this firm.
4.2 Laboratorv Investigation
Specific laboratory tests conducted for this investigation included: In-Place Moisture and
Density, and 200 Wash. Test method descriptions and laboratory results are presented in
Appendix C.
5.0 GEOLOGY
5.1 General Physiographic Setting
The site lies within the coastal area of northem San Diego County. Geomorphically, this area is
characterized by uplifted marine terraces dissected by intermittent streams. More specifically,
the site lies within the Aqua Hedionda Lagoon drainage basin, and is approximately half of a
mile south of the lagoon. Topography at the site slopes down slightly from the street to the east
toward the ocean to the west. The existing building pad elevation at the site is approximately 36
feet above mean sea level (msl).
5.2 Geologic Conditions
Based on mapping compiled by Tan and Kennedy (1996), surface soils near the site consist of
Quatemary Terrace Deposits and Tertiary Santiago Formation. Based on our explorations,
surface and near surface soils consist of fill soils overlying Quatemary Tertace Deposits. It is
anticipated that units of the Tertiary Santiago Formation underlie the Terrace Deposits at depths
greater than 20 feet. The soil descriptions below are based on qualitative and quantitative
attributes of the soils at the site.
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March 2, 2004 CTE Job No. 10-6766
5.2.1 Fill Soils
Fill soils were encountered to a maximum depth explored of approximately five feet
below existing grade. Fill soils appear to be relatively well compacted. These materials
were observed to consist primarily of loose to medium dense, moist, medium yellowish
brown, compacted silty SAND. Fills will require mitigative grading prior to construction
of the proposed improvements as recommended herein.
5.2.2 Ouatemarv Tertace Deposits
Quatemary tertace deposits were observed beneath site fill soils to the maximum depth
explored. These materials generally consist of brown, moist, medium dense to very
dense, poorly grade or silty medium-grained sands. These native materials are suitable
for support of the proposed improvements as recommended herein.
5.3 Groundwater Conditions
Groundwater was not encountered during our explorations to the maximum depth of nineteen
and a half feet at the site. We anticipate groundwater is located at an approximate elevation of
zero feet msl, and may vary with tidal fluctuations. Although groundwater levels may fluctuate,
groundwater is not expected to affect the proposed improvements if proper drainage is
maintained.
5.4 Geologic Hazards
From our investigation it appears that geologic hazards at the site are primarily limited to those
caused by violent shaking from earthquake generated ground motion waves. The potential for
damage from displacement or fault movement beneath the proposed stmctures should be
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March 2, 2004 CTE Job No. 10-6766
considered low. The site is not within a State of Califomia-designated Alquist-Priolo Special
Studies Zone for eeirthquake faults.
5.4.1 Local and Regional Faulting
Based on our site reconnaissance, evidence from our explorations, and a review of
appropriate geologic literature, it is our opinion that the site is not on known active fault
traces. According to the Califomia Division of Mines and Geology, a fault is active if it
displays evidence of activity in the last 11,000 years (Hart and Bryant, 1997).
The Rose Canyon Fault Zone, approximately five kilometers to the west, is the closest
known active fault (Jennings, 1987). Other principal active regional faults include: The
Coronado Banks, San Jacinto, Palos Verdes, San Andreas, and Elsinore Faults.
5.4.2 Site Near Source Factors and Seismic Coefficients
In accordance with the 2001 Califomia Building Code, Volume 2, Figure 16-2, the
referenced site is located within seismic zone 4 and has a seismic zone factor of Z=0.4.
The nearest active fault, the Rose Canyon Fault Zone, is approximately five kilometers to
the west and is considered a Type B seismic source. Based on the distance from the site
to the Rose Canyon Fault Zone, near source factors of Nv=1.2 and Na=1.0 are
appropriate. Based on the shallow subsurface explorations and our knowledge of the
area, the site has a soil profile type of So and seismic coefficients of Cv=0.77 and
Ca=0.44.
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5.4.3 Tsunami and Seiche Damage
The potential for tsunami damage at the can not be precluded, based on the site's
elevation (approximately 30 feet above sea level) and distance from the ocean. However,
according to McCuUough (1985) the potential for 100 and 500 years tsunami events is
four and six feet. This suggests that there is a very low probability of site damage due to
the elevation of the building pad of the site (approximately 36 feet above msl).
Seismically induced seiche (oscillatory waves) damage is also considered unlikely for the
reasons stated above.
5.4.4 Landsliding or Rocksliding
According to Tan and Giffen (1995), the site area is generally susceptible to landsliding.
However, we did not observe active landslides or rockslides at the site. Landslides have
not been mapped near the site area (Tan and Keimedy, 1996). We anticipate that the
potential for landsliding or rocksliding to affect the site during its design life is
negligible.
5.4.5 Compressible and Expansive Soils
Based on geologic observation and laboratory testing of onsite soils, the fill materials
generally exhibit low to moderate compressibility and low expansive characteristics (EI
less than 30). Compressible fill materials will be mitigated via overexcavation and
recompaction. Underlying native materials are generally non-compressible and non-
expansive. Furthermore, native materials do not appear to be subject to significant
seismic settlement; therefore, these materials are considered suitable for support of
proposed improvements.
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March 2, 2004 CTE Job No. 10-6766
5.4.6 Liquefaction Evaluation
Liquefaction occurs when saturated fine-grained sands or silts lose their physical strength
during earthquake-induced shaking and behave as a liquid. This is due to loss of point-
to-point grain contact and transfer of normal stress to the pore water. Liquefaction
potential varies with groundwater level, soil type, material gradation, relative density, and
the intensity and duration of groimd shaking.
The potential for damage to the site from liquefaction of site soils is considered low.
This is based on the depth to groundwater and the generally medium dense nature of
underlying native soils in the area. Appendix B presents the results of our quantitative
liquefaction analysis (Civiltech, 2003).
5.4.7 Seismic Settlement Evaluation
Seismic settlement occurs when loose to medium dense granular soils densify during
seismic events. We anticipate that topsoils and/or loose or soft surficial soils will be
mitigated during site grading. The upper 10 to 15 feet of native materials at the site were
generally found to be medium dense, but may experience very minor seismic settlement.
Based on our evaluation, the building pad area of the site could experience considerably
less than 0.5 inches of total settlement as a result of seismic settlement of dry sands. The
recommended uniform layer of engineered fill beneath the site and the foundation
recommendations herein will adequately mitigate adverse effects of differential
settlement of deeper native soils in the unlikely event of a major earthquake in the
immediate vicinity of the site. Therefore, in our opinion, the potential for seismic
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Proposed Improvements to McGuire Residence
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March 2, 2004 CTE Job No. 10-6766
settlement resulting in damage to site improvements should be considered low.
Appendix B presents the results of our quantitative liquefaction analysis.
5.4.8 Cortosive Soils
Due to marine envirorunent, onsite soils are anticipated to be moderately too highly
cortosive to both concrete and fcrtous metals. CTE does not practice cortosion
engineering. Therefore, a cortOsion specialist shall be consulted if additional
investigation and/or evaluation are deemed necessary by the project architect or structural
engineer.
5.4.9 Bluff Erosion and Setbacks
As previously indicated, due to the low site elevation (approximately 36 feet msl) and the
current layback of multiple moderate slopes, the site is not anticipated to be significantly
impacted by the widespread coastal bluff erosion that typically results in relatively fast-
paced coastline collapse and/or recession in the northem areas of San Diego County. In
addition, some riprap materials, consisting of large intact boulders, rest along the
shoreline of the site; these materials provide significant additional ocean wave protection
to the site, especially during significant storm and/or associated storm-surge.
Nevertheless, erosion of all coastal areas and shoreline retreat is inevitable, especially
over extended periods of time.
Based on the information provided above, as well as our understanding of the proposed
improvements, it is our opinion that proposed building improvements need not be
excessively setback from the existing "top of bluff location. However, foundations shall
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Proposed Improvements to McGuire Residence
5035 Tierta Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
have adequate setback/embedment as recommended in the subsequent sections of this
report.
6.0 CONCLUSIONS AND RECOMMENDATIONS
6.1 General
We conclude that the proposed constmction on the site is feasible from a geotechnical
standpoint, provided the recommendations in this report are incorporated into the design and
constmction of the project.
Based on our subsurface investigation and engineering analysis, the proposed improvements can
be supported on spread foundations designed and constmcted as recommended herein. However,
preparatory site grading will be required. Specific recommendations for the design and
construction of improvements at the subject site are included in the subsequent sections of this
report.
6.2 Site Preparation
6.2.1 General
The site should be cleared of any debris and other deleterious materials. In areas to
receive engineered fill, stmctures or distress-sensitive improvements, expansive, surficial
eroded, desiccated, burrowed, or otherwise loose or disturbed soils should be removed to
the depth of competent native material and to a minimum depth of five feet below
existing or proposed building pad elevations, whichever is deeper. Based on our onsite
explorations, we anticipate uniform removals of five feet below existing grades will
generally be adequate. However, localized areas of deeper removals may be required. In
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Proposed Improvements to McGuire Residence
5035 Tierta Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
addition, any materials disturbed during demolition of existing site improvements shall be
completely removed and replaced as engineered fill. Organic and other deleterious
materials not suitable for stmctural backfill should be disposed of offsite at a legal
disposal site.
Prior to placing any engineered fill, exposed subgrade shall be scarified, moisture
conditioned to near optimum moisture content, and properly recompacted. General
engineered fill shall be compacted to a minimum 90% relative compaction (per ASTM D
1557) at the near optimum moisture contents.
6.2.2 Site Excavations
Site excavations can generally be accomplished using heavy-duty constmction
equipment. Design recommendations for temporary constmction slopes are provided in a
subsequent section of this report. Site excavations should be observed by CTE. Such
observations are essential to identify field conditions that differ from those identified
during our subsurface investigation and to adjust designs to actual field conditions
encountered.
6.2.3 Fill Placement and Compaction
As stated, an engineer or geologist from CTE should be called upon to verify that the
proper site preparation has occurred before fill placement begins. As stated, following
the recommended removals, areas to receive fills or improvements should be scarified,
moisture conditioned near optimum moisture content, and properly recompacted.
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March 2, 2004 CTE Job No. 10-6766
General fill and backfill should be compacted to a minimum relative compaction of 90%
as evaluated by ASTM D-1557 (except in pavement areas) at moisture contents near
optimum (generally within two percent). The optimum lift thickness for backfill soil will
be dependent on the type of compaction equipment used. Generally, backfill should be
placed in uniform lifts not exceeding eight inches in loose thickness. If proposed, sloping
backfill shall be properly keyed and benched. Backfill placement and compaction should
be done in overall conformance with geotechnical recommendations and local
ordinances. All grading shall be performed in accordance with the regulations of the
goveming authorities.
6.2.4 Fill Materials
Soils derived from on-site materials are considered suitable for reuse on the site as fill,
provided they are screened of significant organic materials and materials greater than
three inches in maximum dimension, if encountered.
Imported fill beneath stmctures, pavements and walks should have an expansion index
less than or equal to 30 (per UBC 18-I-B) with less than 35% passing the no. 200 sieve.
Imported fill soils for use in stmctural or slope areas should be evaluated by the soils
engineer to determine strength characteristics before placement on the site.
6.3 Temporary Constmction Slopes
Sloping recommendations for unshored temporary excavations are provided herein. The
recommended slopes should be relatively stable against deep-seated failure, but may experience
localized sloughing. Recommended slope ratios are set forth in Table 1.
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5035 Tierta Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE JobNo. 10-6766
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SOILS TYPE SLOPE RATIO
(Horizontal: Vertical)
MAXIMUM HEIGHT
B (Quatemary Terrace Deposits) 1:1 (MAXIMUM) 8 FEET
Actual field conditions and soil type designations must be verified by a "competent person"
while excavations exist according to Cal-OSHA regulations. In addition, the above sloping
recommendations do not allow for potential water seepage, or surcharge loading at the top of
slopes by vehicular traffic, equipment or materials. Appropriate surcharge setbacks must be
maintained from the top of all unshored slopes. Excavations shall not encroach within a 1:1
plane extended down from adjacent stmctures to remain.
6.4 Foundations and Slab Recommendations
6.4.1 General
The following recommendations are for preliminary planning purposes only. These
foundation recommendations should be reviewed after completion of earthwork and
testing of surface soils.
We anticipate all foundations for proposed stmctures will be founded entirely in properly
compacted engineered fill materials. Foundations should not straddle transitional
conditions (changes from cut to fill soils).
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6.4.2 Spread Foundations and Slabs-on-Grade
Continuous and isolated spread footings are suitable for use at this site. We anticipate
that all building footings will be founded entirely in properly compacted fills as
recommended herein. Foundation dimensions and reinforcement should be based on
allowable bearing values of 2,500 pounds per square foot (psf) for footings embedded a
minimum of 18 inches in properly recompacted fill materials. The allowable bearing
value may be increased by one third for short duration loading which includes the effects
of wind or seismic forces.
Minimum footing reinforcement for continuous footings should consist of four No. 4
reinforcing bars; two placed near the top and two placed near the bottom or as per the
project structural engineer. The structural engineer should design isolated footing
reinforcement. It is recommended that isolated footings be coimected to each other or
adjacent continuous foundations via minimum 12-inch by 12-inch tie beams with
minimum reinforcing steel percentages.
As a precautionary measure, it is generally recommended that all foundations attain a
minimum 15-foot horizontal distance to daylight. Deepening of locally affected
foundations may be a suitable means of attaining the prescribed foundation setbacks.
Lightly loaded concrete slabs should be a minimum of five inches thick. Minimum slab
reinforcement should consist of #4 reinforcing bars placed on 24-inch centers, each way,
at mid-slab height. Moisture sensitive floor areas shall be underlain by a minimum 10-
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March 2, 2004 CTE Job No. 10-6766
mil visqueen layer, with all laps sealed or taped. Slabs subjected to heavier loads may
require thicker slab sections and/or increased reinforcement.
6.4.3 Foundation Settlement
Based on the preliminary plans as well as the conditions observed at the site, the
maximum total static settlement is expected to be less than 1.0 inches and the maximtim
differential static settlement is expected to be less than 0.5 inches. Total and differential
dynamic settlements are anticipated to be less than 0.5 inches, and will not likely affect
the proposed improvements.
6.5 Lateral Resistance and Earth Pressures
Foundations placed in firm, well-compacted fill material may be designed using a coefficient of
friction of 0.35 (total frictional resistance equals the coefficient of friction times the dead load).
A design passive resistance value of 250 pounds per square foot per foot of depth (with a
maximum value of 1,000 pounds per square foot) may be used. The allowable lateral resistance
can be taken as the sum of the frictional resistance and the passive resistance, provided the
passive resistance does not exceed two-thirds of the total allowable resistance.
Walls below grade up to ten feet high and backfilled using granular soils may be designed using
the equivalent fluid weights given in Table 2 below. If segmental block walls are proposed at the
site, our office shall be contacted and additional design and constmction recommendations will
be provided upon request.
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TABLE2
EQUIVALENT FLUID UNIT WEIGHTS
(pounds per cubic foot)
m
WALL TYPE LEVEL BACKFILL SLOPE BACKFILL
m 2:1 (HORIZONTAL: VERTICAL)
m CANTILEVER WALL 35 55
m (YIELDING)
m RESTRAINED WALL 55 85
The above values assume non-expansive backfill and free draining conditions. Measures should
be taken to prevent a moisture buildup behind all walls below grade. Drainage measures should
include free draining backfill materials and perforated drains. Drains should discharge to an
appropriate offsite location.
We recommend that walls below grade be backfilled with soils having an expansion index of 20
or less. The backfill area should include the zone defined by a 1:1 sloping plane, extended back
from the base of the wall. Wall backfill should be compacted to at least 90 percent relative
compaction, based on ASTM Dl557-91. Backfill should not be placed imtil walls have achieved
adequate structural strength. Heavy compactors, which could cause distress to walls, should not
be used.
6.6 Exterior Flatwork
To reduce the potential for distress to exterior flatwork caused by minor settlement of foundation
soils, we recommend that such flatwork be reinforced and installed with crack-control joints at
appropriate spacing as designed by the project architect. The upper 12 inches of subgrade should
be properly recompacted before placing concrete. Flatwork shall be a minimum four inches
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thick. We recommend flatwork be reinforced with minimum #3 rebar spaced at 18 inches, on
center, both ways. Reinforcing shall be located near mid-height of the concrete section.
6.7 Vehicular Pavements
The proposed development may include the constmction of pavement areas. Presented in Table
3 below are recommended pavement sections. Two options are presented. Option 1 is for
construction of asphalted concrete pavements; Option 2 is for constmction of full-depth concrete
pavements.
The pavement sections presented are based on estimated traffic indices and the design value for
the Resistance "R"- Value of onsite materials. The upper 12 inches of subgrade and all base
materials shall be compacted to 95% of laboratory detennined maximum dry density, as per
ASTM D1557, at moisture contents near optimum.
I'KI LIMIN \RV RELilMMFNUni) P-Wl MI NT I Ilk KNI
Traffic Area Assumed Traffic
Index
Preliminary
Subgrade
"R"-Value
Option 1:
Asphalt Pavements
Option 2:
Full
Depth
Concrete
Pavements
(inches)
Traffic Area Assumed Traffic
Index
Preliminary
Subgrade
"R"-Value AC
Thickness
(inches)
Class II
Aggregate Base
Thickness
(inches)
Option 2:
Full
Depth
Concrete
Pavements
(inches)
Drive and 4.5 25 2.5 4.0 5.5
Parking Areas or or
4.0 0.0
At the owner's option, upon completion of preparatory grading in the proposed pavement areas,
additional subgrade sampling and testing for "R" Value determination can be conducted. This
F:\l 0-6766\Rpt_Geotech.doc
Preliminary Geotechnical Investigation Page 18
Proposed Improvements to McGuire Residence
5035 Tierra Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
additional testing will enable us to modify the pavement sections based on the as-graded
conditions, if necessary.
6.8 Drainage
Surface runoff should be collected and directed away from improvements by means of
appropriate erosion reducing devices and positive drainage should be established around the
proposed improvements. Positive drainage should be directed away from improvements at a
gradient of at least two percent for a distance of at least five feet. Surficial contours within the
area should keep water from affecting the foundations provided planter areas are not over
watered. The project civil engineer should evaluate the on-site drainage and make necessary
provisions to keep surface water from affecting the site.
6.9 Slopes
Slopes should be constmcted at 2:1 (horizontal: vertical) or flatter. Although graded slopes on
this site will be grossly stable (i.e., factor of safety greater than 1.5), the soils will be somewhat
erodible. Therefore, runoff water should not be permitted to drain over the edges of slopes
unless that water is confined to properly designed and constmcted drainage facilities. Erosion
resistant vegetation should be maintained on the face of all slopes. As previously stated, all
slopes shall be properly keyed and benched.
Typically, soils along the top portion of a fill slope face will tend to creep laterally. We do not
recommend that distress sensitive landscape improvements be constructed within five feet of
slope crests in fill areas.
F:\l 0-6766\Rpt_Geotech.doc
Preliminary Geotechnical Investigation Page 19
Proposed Improvements to McGuire Residence
5035 Tierra Del Oro Street, Carlsbad, Califomia
March 2, 2004 CTE Job No. 10-6766
6.10 Construction Observation
The recommendations provided in this report are based on preliminary design information for the
proposed constmction and the subsurface conditions fovmd in the exploratory boring locations.
The interpolated subsurface conditions should be checked in the field during constmction to
verify that conditions are as anticipated.
Recommendations provided in this report are based on the understanding and assumption that
CTE will provide the observation and testing services for the project. All earthwork should be
observed and tested to verify that grading activity has been performed according to the
recommendations contained within this report. All foundation excavations shall be evaluated by
the project engineer before reinforcing steel placement.
6.11 Plan Review
CTE should review all project grading and foundation plans before the start of earthworks to
identify potential conflicts with the recommendations contaihed in this report.
7.0 LIMITATIONS OF INVESTIGATION
The recommendations provided in this report are based on the anticipated construction and the
subsurface conditions found in our explorations. The interpolated subsurface conditions should
be checked in the field during constmction to verify that conditions are as anticipated.
Recommendations provided in this report are based on the understanding and assumption that
CTE will provide the observation and testing services for the project. All earthworks should be
observed and tested to verify that grading activity has been performed according to the
F:\l 0-6766\Rpt_Geotech.doc
Preliminary Geotechnical Investigation
Proposed Improvements to McGuire Residence
5035 Tierta Del Oro Street, Carlsbad, California
March 2, 2004
Page 20
CTE JobNo. 10-6766
recommendations contained within this report. The project engineer should evaluate all footing
trenches before reinforcing steel placement.
The field evaluation, laboratory testing and geotechnical analysis presented in this report have
been conducted according to cmrent engineering practice and the standard of care exercised by
reputable geotechnical consultants performing similar tasks in this area. No other wananty,
expressed or implied, is made regarding the conclusions, recommendations and opinions
expressed in this report. Variations may exist and conditions not observed or described in this
report may be encountered during constmction.
Our conclusions and recommendations are based on an analysis of the observed conditions. If
conditions different from those described in this report are encountered, our office should be
notified and additional recommendations, if required, will be provided upon request. We
appreciate this opportunity to be of service on this project. If you have any questions regarding
this report, please do not hesitate to contact the undersigned.
Respectfully submitted,
CONSTRUCTION TESTING & ENGINEERING, INC.
T. Math, RCE #61013
Senior Engineer
Jay F. Lynch, CES #1890
Senior Geologist^
F:\10-6766\Rpt_Geotech.doc
117°21.000' W
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liNGINEERING.INC
CONSTRUCTION TESTING & ENGINEERING, INC.
GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION
2414 VINEYARD AVENUE, STE G ESCONDIDO CA. 92029 (760) 74fr4955
SITE INDEX MAI*
Proposed McGuire's Residence
5035 Tierra Del Oro Street
Carlsbad, Califomia
CTCJOBNO
10-6766 SCALE: AS SHOWN
FIGURE;
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B-1
APPROXIMATE BORING LOCATION
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EXPLORATION LOCATION MAP
Mc OXME RESIDENCE
5035 HERRA DEL ORO
CARLSBAD, CALIFORNLA
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03/04
APPENDIX A
REFERENCES CITED
F:\10-6766\PRELIMINARY GEOTECHNICAL investigation.doc
REFERENCES CITED
1. Hart, Earl W. and Bryant, W.A., 1997, "Fault-Rupture Hazard Zones in Califomia,
Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones
Maps," Califomia Division of Mines and Geology, Special Publication 42.
2. Jennings, C. W., 1987, "Fault Map of Califomia with Locations of Volcanoes, Thermal
Springs and Thermal Wells."
3. Tan, S. S., and Giffen, D.G., 1995, "Landslide Hazards in the Northem Part ofthe San
Diego Metropolitan Area, San Diego County, Califomia: Landslide Hazard Identification
Map", Califomia Department of Conservation, Division of Mines and Geology, Open-
File Report 95-04, State of Califomia, Division of Mines and Geology, Sacramento,
Califomia.
4. LiquifyPro, Version 4, Civiltech Corporation, 2003, "Computer Program for Evaluation
of Liquefaction Potential and Calculations of Settlement of Soil Deposits Due to Seismic
Loads per NCEER Workshop and SPI 17 Implementation."
5. McCulloch, D.S., 1985, "Evaluating Tsunami Potential" in Ziony, J.L, ed.. Evaluation
Earthquake Hazards in Los Angeles Region - An Earth-Science Perspective, U.S.
Geological Survey Professional Paper 1360
6. Tan, S. S., and Kennedy M., 1996, "Geological Map of the Oceanside and San Marcos
7.5' Quadrangles", Geological Maps of the Northwestem Part of San Diego County,
California, Califomia Department of Conservation, Division of Mines and Geology.
7. Uniform Building Code, 1997, Maps of Known Active Fault Near-Source Zones in
Califomia and Adjacent Portions of Nevada.
F:\10-6766\Rpt_Geotech.doc
APPENDIX B
EXPLORATION LOGS AND LIQUEFACTION ANALYSIS
F:\10-6766\Rpt_Geotech.doc
>>^CONSTRUCTION TESTING & ENGINEERING, INC,
GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION
2414 VINEYARD AVENUE. SUITE G ESCONDIDO CA 92029 (760) 746-4955
EKGINZERING.INC
DEFINITION OF TERMS
PRIMARY DIVISIONS SYMBOLS SECONDARY DIVISIONS
if)
o o
tn tu
5 X
< > • w ^ S= " « S J2
5 o
f- -J o
< (N
2 d
<
2
GRAVELS
MORE THAN
HALF OF
COARSE
FRACTION IS
LARGER THAN
NO. 4 SIEVE
SANDS
MORE THAN
HALF OF
COARSE
FRACTION IS
SMALLER THAN
NO. 4 SIEVE
CLEAN
GRAVELS
< 5% FINES GP ^Ij*
WELL GRADED GRAVELS, GRAVEL-SAND MIXTURES
LITTLE OR NO FINES
POORLY GRADED GRAVELS OR GRAVEL SAND MIXTURES,
LITTLE OF NO FINES
SILTY GRAVELS, GRAVEL-SAND-SILT MIXTURES,
NON-PLASTIC FINES
CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES,
PLASTIC FINES
WELL GRADED SANDS. GRAVELLY SANDS, LITTLE OR NO
FINES
POORLY GRADED SANDS, GRAVELLY SANDS, LITTLE OR
NO FINES
SILTY SANDS, SAND-SILT MIXTURES, NON-PLASTIC FINES
CLAYEY SANDS, SAND-CLAY MIXTURES, PLASTIC FINES
t/3 u.
a 5 w z.
J Zn SILTS AND CLAYS
LIQUID LIMIT IS
LESS THAN 50
INORGANIC SILTS, VERY FINE SANDS, ROCK FLOUR, SILTY
OR CLAYEY FINE S/WDS, SLIGHTLY PLASTIC CLAYEY SILTS
INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,
GRAVELLY, SANDY, SILTS OR LEAN CLAYS
ORGANIC SILTS AND ORGANIC CLAYS OF LOW PLASTICITY
SILTS AND CLAVS
LIQUID LIMIT IS
GREATER THAN 50
INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS FINE
SANDY OR SILTY SOILS, ELASTIC SILTS
INORGANIC CLAYS OF HIGH PLASTICITY, FAT CLAYS
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTY CLAYS
HIGHLY ORGANIC SOILS PEAT AND OTHER HIGHLY ORG/VNIC SOILS
GRAIN SIZES
BOULDERS COBBLES GRAVEL
COARSE FINE
SAND
COARSE MEDIUM FINE SILTS AND CLAYS
12" 3" 3/4"
CLEAR SQUARE SIEVE OPENING
4 10 40 200
U.S. STANDARD SIEVE SIZE
ADDITIONAL TESTS
(OTHER THAN TEST PIT AND BORING LOG COLUMN HEADINGS)
MAX- Maximum Dry Density
GS- Grain Size Distribution
SE- Sand Equivalent
EI- Expansion Index
CHM- Sulfate and Chloride
Content, pH, Resistivity
COR - Corrosivity
PM- Permeability
SG- Specific Gravity
HA- Hydrometer Analysis
AL- Atterberg Limits
RV- R-Value
CN- Consolidation
PP- Pocket Penetrometer
WA- Wash Analysis
DS- Direct Shear
UC- Unconfined Compression
MD- Moisture/Density
M- Moisture
SC- Swell Compression
01- Organic Impurities
FIGURE:| BLl
#f%,CONSTRUCTION TESTING & ENGINEERING, INC.
I \.», GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTINO AND INSPECTION
2414 VINEYARD AVENUE. SUITE G ESCONDIDO CA. 92029 (760) 746-4955
fihG]NEEKlNC.rNC
PRaiECT:
CTE .IOB NO:
LOGGED BY:
DRILLER:
DRILL METHOD:
SAMPLE METHOD:
SHEET:
DRILLING DATE:
ELEVATION:
Of
o
&
a
o
01)
o
5
BORING LEGEND
DESCRIPTION
Laboratory Tests
i
il
-5-
10-
/
-15-
•20-
•25-
"SM"
Block or Chunk Sample
Bulk Sample
Standard Penetration Test
Modified Split-Barrel Drive Sampler (Cal Sampler)
Thin Walled Army Corp. of Engineers Sample
Groundwater Table
Soil Type or Classification Change
7 —
V Formation Change KApproximate boundaries queried (?)1
Ouotes are placed around classifications where the soils
exist in situ as bedrock
FIGURE: | BL2
#r%C0NSTRUCT10N TESTING & ENGINEERING, INC,
* GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION
2414 VINEYARD AVENUE, SUITE G ESCONDIDO CA. 9202 9 (760) 746-4 9 55 EKOINEERIKGJNC
PROJECT.
CTE .108 NO;
LOGGED BY:
MCGUIRE RESIDENCE
10-6766
D. RIES
DRILLER:
DRILL METHOD:
SAMPLE METHOD:
PACIFIC DRILLING
TRIPOD RIG
BULK, CAL RINGS, SPT
SHEET; I
DRILLING DATE:
ELEVATION;
of 1
2/25/2004
DQ
Q
Q o
s O
BORING: B-1
DESCRIPTION
Laboratory Tests
-0-
SM
0-0.2' Grass/Turf
0.2'-@ 5.0'Fill
Medium yellowish brown, loose to medium dense, moist, silty
SAND (SM)
^0-
45-
10
12
15
105.7 6.9
SM
@ 5' Ouatemarv Teirace Deposits:
Medium brovm, medium dense slightly moist, SAND with SILT
(SM), fine to medium grained.
MD
@ 7' becomes SAND (SP)
10
SP Light yellowish, rusty orange brown, and dark gray to black layers,
medium dense, slightly moist, fine to medium SAND (SP), trace
SILT
WA
10
10
15
20
30
30
SP
SP
Light yellowish, rusty orange brown, and dark gray to black layers,
very dense, slightly moist, fine to medium SAND (SP), trace
SILT
Light yellowish, rusty orange brown, and dark gray to black layers,
very dense, slightly moist, fine to medium SAND (SP), trace
SILT, dense
WA
50-Total depth 19.5'
No Groundwater
Hole Backfilled
-25-
Boring B-1
^CONSTRUCTION TESTING & ENGINEERING, INC.
GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION
2414 VINEYARD AVENUE, SUITE 0 ESCONDIDO CA. 92029 (760) 746 .4955
E^"CINEERI^"OJNC
PROJECT;
CTE JOB NO;
LOGGED BY;
MCGUIRE RESIDENCE
10-6766
D. RIES
DRILLER:
DRILL METHOD:
SAMPLE METHOD;
PACIFIC DRILLING
TRIPOD RIG
BULK, CAL RINGS, SPT
SHEET: I
DRILLING DATE;
ELEVATION;
of 1
2/25/2004
Q
o
s
t/5
O BORING: B-2
DESCRIPTION
Laboratory Tests
-5-
-10-
12
15
5
6
6
9
10
10
12
2
30
30/4"
SM
SM
O-r Fill/Topsoil: Dark brown, loose, moist, silty, SAND (SM)
with organics.
@ r Ouatemarv Terrace /deposits:
Brown medium dense, moist, silty SAND (SM).
WA
Brown medium dense, moist, less silt SAND (SM).
SM Brown medium dense, moist, less silt SAND (SM).
SP Yellowish brown, medium dense, slightly moist, SAND (SP)
fine to medium grained.
Yellowish brown, very dense, slightly moist, SAND (SP)
fine to medium grained.
WA
20-
-25-
Total depth 19.5'
No Groundwater
Hole Backfilled
LIQUEFACTION ANALYSIS
MCGUIRE RESIDENCE
Hole No.=B-1 Water Depth=3€ ft Surface Elev.-~36
•%
Shear Stress Ratio
0
10
20
- 30
40
50
1 r "1 r
Factor of Safety
10 1 5
llllll
fs=1
Settlement
0 (in.) 1
I II I II I I r
CRR CSR
Shaded Zone has Liquefaction Potential
Raw Unit Fines SPT Weight %
17 115 5
16 115 4.3
25 115 5
60 115 5
Wet— Dry-
S = 0.06 in.
50 115 5
Magnitude=6.9
Acceleration=30g
Soil Description
60
70
CivilTech Corporation Boring B-1 Plate B-1
LIQUEFACTION ANALYSIS
MCGUIRE RESIDENCE
Hole No. =B-2 Water Depth=35 ft Surface Elev. =~35
i Shear Sfress Rafo
(ft)^ 0
10
20
i— 30
40
50
"I I I r "T I r
Factor of Safefy
10 1 5
lllllllll
fs=1
Settlement
0 (in.) 1
IIIII TT
CRR CSR
Raw Unit Fines
SPT Weight %
12 115 15
19 115 3.8
22 115 5
60 115 5
Shaded Zone has Liquefaction Potential
Wet— Dry-
S = 0.06 in.
50 115 5
Magnitude=6.9
Acceleratlon=.30g
Soil Description
I 60
tn t_
5
70
CivilTech Corporation Boring B-2 Plate B-2
APPENDIX C
LABORATORY METHODS AND RESULTS
••I
m
F:\10-6766\PRELIMINARY GEOTECHNICAL investigation.doc
APPENDIX C
LABORATORY METHODS AND RESULTS
Laboratory tests were performed on representative soil samples to detect their relative
engineering properties. Tests were performed following test methods of the American Society
for Testing Materials or other accepted standards. The following presents a brief description of
the various test methods used. Laboratory results are presented in the following section of this
Appendix.
Classification
Soils were classified visually according to the Unified Soil Classification System. Visual
classifications were supplemented by laboratory testing of selected samples according to ASTM
D2487.
Particle-Size Analysis
Particle-size analyses were performed on selected representative samples according to ASTM
D422.
F:\10-6766\PRELIMINARY GEOTECHNICAL investigation.doc
^CONSTRUCTION TESTING & ENGINEERING, INC.
''' GEOTECHNICAL AND CONSTRUCTION ENGINEERING TESTING AND INSPECTION
2414 VINEYARD AVENUE. SUITE G ESCONDIDO CA. 92029 (760) 746-4955
EKGINEERINC.INC
200 WASH ANALYSIS
LOCATION DEPTH
(feet)
MATERIAL PASSING
200 SIEVE (%)
CLASSIFICATION
m B-1 10.0 4.3 SP
B-1 19.0 5.0 SP
B-2 3.5 19.4 SM
m B-2 15.0 3.8 SP
•mi
IN-PLACE MOISTURE AND DENSITY
•m LOCATION DEPTH MOISTURE DRY DENSITY
m (feet) (%)
B-1 5.0 6.9 105.7
LABORATORY SUMMARY CTR IOR NO. 10-6766
^ APPENDIX D
STANDARD SPECIFICATIONS FOR GRADING
•m
^ F;\I0-6766\PRELIMrNARY GEOTECHNICAL investigation.doc
Appendix D Page D-1
Standard Grading Specifications
Section 1 - General
The guidelines contained herein represent Constmction Testing & Engineering's standard
recommendations for grading and other associated operations on constmction projects. These
guidelines should be considered a portion of the project specifications. Recommendations
contained in the body of the previously presented soils report shall supersede the
recommendations and or requirements as specified herein. The project geotechnical consultant
shall interpret disputes arising out of interpretation of the recommendations contained in the soils
report or specifications contained herein.
Section 2 - Responsibilities of Proiect Personnel
The geotechnical consultant should provide observation and testing services sufficient to assure
that geotechnical constmction is performed in general conformance with project specifications
and standard grading practices. The geotechnical consultant should report any deviations to the
client or his authorized representative.
The Client should be chiefly responsible for all aspects of the project. He or his authorized
representative has the responsibility of reviewing the findings and recommendations of the
geotechnical consultant. He shall authorize or cause to have authorized the Contractor and/or
other consultants to perform work and/or provide services. During grading the Client or his
authorized representative should remain on-site or should remain reasonably accessible to all
concerned parties in order to make decisions necessary to maintain the flow of the project.
The Contractor should be responsible for the safety of the project and satisfactory completion of
all grading and other associated operations on constmction projects, including, but not limited to,
earth work in accordance with the project plans, specifications and controlling agency
requirements.
Section 3 - Preconstmction Meeting
A preconstruction site meeting shall be artanged by the owner and/or client and shall include the
grading contractor, the design engineer, the geotechnical consultant, owner's representative and
representatives of the appropriate goveming authorities.
Section 4 - Site Preparation
The client or contractor should obtain the required approvals from the controlling authorities for
the project prior, during and/or after demolition, site preparation and removals, etc. The
appropriate approvals should be obtained prior to proceeding with grading operations.
Clearing and gmbbing should consist of the removal of vegetation such as bmsh, grass, woods,
stumps, trees, root of trees and otherwise deleterious natural materials firom the areas to be
graded. Clearing and gmbbing should extend to the outside of all proposed excavation and fill
areas.
Demolition should include removal of buildings, stmctures, foundations, reservoirs, utilities
(including underground pipelines, septic tanks, leach fields, seepage pits, cisterns, mining shafts,
tunnels, etc.) and other man-made surface and subsurface improvements from the areas to be
graded. Demolition of utilities should include proper capping and/or rerouting pipelines at the
project perimeter and cutoff and capping of wells in accordance with the requirements of the
goveming authorities and the recommendations of the geotechnical consultant at the time of
demolition.
F:\10-6766\PRELIMINARY GEOTECHNICAL investigation.doc
Appendix D Page D-2
Standard Grading Specifications
Trees, plants or man-made improvements not planned to be removed or demolished should be
protected by the contractor from damage or injury.
Debris generated during clearing, gmbbing and/or demolition operations should be wasted from
areas to be graded and disposed off-site. Clearing, grubbing and demolition operations should be
performed under the observation of the geotechnical consultant.
Section 5 - Site Protection
Protection of the site during the period of grading should be the responsibility of the contractor.
Unless other provisions are made in writing and agreed upon among the concemed parties,
completion of a portion of the project should not be considered to preclude that portion or
adjacent areas from the requirements for site protection until such time as the entire project is
complete as identified by the geotechnical consultant, the client and the regulating agencies.
Precautions should be taken during the performance of site clearing, excavations and grading to
protect the work site from flooding, ponding or inundation by poor or improper surface drainage.
Temporary provisions should be made during the rainy season to adequately direct surface
drainage away firom and off the work site. Where low areas cannot be avoided, pumps should be
kept on hand to continually remove water during periods of rainfall.
Rain related damage should be considered to include, but may not be limited to, erosion, silting,
saturation, swelling, structural distress and other adverse conditions as determined by the
geotechnical consultant. Soil adversely affected should be classified as unsuitable materials and
should be subject to overexcavation and replacement with compacted fill or other remedial
grading as recommended by the geotechnical consultant.
The contractor should be responsible for the stability of all temporary excavations.
Recommendations by the geotechnical consultant pertaining to temporary excavations (e.g.,
backcuts) are made in consideration of stability of the completed project and, therefore, should
not be considered to preclude the responsibilities of the contractor. Recommendations by the
geotechnical consultant should not be considered to preclude requirements that are more
restrictive by the regulating agencies. The contractor should provide during periods of extensive
rainfall plastic sheeting to prevent unprotected slopes from becoming saturated and unstable.
When deemed appropriate by the geotechnical consultant or goveming agencies the contractor
shall install checkdams, desilting basins, sand bags or other drainage control measures.
In relatively level areas and/or slope areas, where saturated soil and/or erosion gullies exist to
depths of greater than 1.0 foot; they should be overexcavated and replaced as compacted fill in
accordance with the applicable specifications. Where affected materials exist to depths of 1.0
foot or less below proposed finished grade, remedial grading by moisture conditioning in-place,
followed by thorough recompaction in accordance with the applicable grading guidelines herein
may be attempted. If the desired results are not achieved, all affected materials should be
overexcavated and replaced as compacted fill in accordance with the slope repair
recommendations herein. If field conditions dictate, the geotechnical consultant may
recommend other slope repair procedures.
Section 6 - Excavations
F;\10-6766\PREL1MINARY GEOTECHNICAL investigation.doc
Appendix D Page D-3
Standard Grading Specifications
6.1 Unsuitable Materials
Materials that are unsuitable should be excavated under observation and recommendations of the
geotechnical consultant. Unsuitable materials include, but may not be limited to, dry, loose, soft,
wet, organic compressible natural soils and fractured, weathered, soft bedrock and
nonengineered or otherwise deleterious fill materials.
Material identified by the geotechnical consultant as unsatisfactory due to its moisture conditions
should be overexcavated; moisture conditioned as needed, to a uniform at or above optimum
moisture condition before placement as compacted fill.
If during the course of grading adverse geotechnical conditions are exposed which were not
anticipated in the preliminary soil report as determined by the geotechnical consultant additional
exploration, analysis, and treatment of these problems may be recommended.
6.2 Cut Slopes
Unless otherwise recommended by the geotechnical consultant and approved by the regulating
agencies, permanent cut slopes should not be steeper than 2:1 (horizontal: vertical).
The geotechnical consultant should observe cut slope excavation and if these excavations expose
loose cohesionless, significantly fractured or otherwise unsuitable material, the materials should
be overexcavated and replaced with a compacted stabilization fill. If encountered specific cross
section details should be obtained from the Geotechnical Consultant.
When extensive cut slopes are excavated or these cut slopes are made in the direction of the
prevailing drainage, a non-erodible diversion swale (brow ditch) should be provided at the top of
the slope.
6.3 Pad Areas
All lot pad areas, including side yard terrace containing both cut and fill materials, transitions,
located less than 3 feet deep should be overexcavated to a depth of 3 feet and replaced with a
uniform compacted fill blanket of 3 feet. Actual depth of overexcavation may vary and should
be delineated by the geotechnical consultant during grading.
For pad areas created above cut or natural slopes, positive drainage should be established away
from the top-of-slope. This may be accomplished utilizing a berm drainage swale and/or an
appropriate pad gradient. A gradient in soil areas away from the top-of-slopes of 2 percent or
greater is recommended.
Section 7 - Compacted Fill
All fill materials should have fill quality, placement, conditioning and compaction as specified
below or as approved by the geotechnical consultant.
7.1 Fill Material Oualitv
Excavated on-site or import materials which are acceptable to the geotechnical consultant may
be utilized as compacted fill, provided trash, vegetation and other deleterious materials are
removed prior to placement. All import materials anticipated for use on-site should be sampled
tested and approved prior to and placement is in conformance with the requirements outlined.
F:\I0-6766\PRELIMINARY GEOTECHNICAL investigation.doc
m
m
Appendix D Page D-4
Standard Grading Specifications
Rocks 12 inches in maximum and smaller may be utilized within compacted fill provided
sufficient fill material is placed and thoroughly compacted over and around all rock to effectively
fill rock voids. The amount of rock should not exceed 40 percent by dry weight passing the 3/4-
inch sieve. The geotechnical consultant may vary those requirements as field conditions dictate.
Where rocks greater than 12 inches but less than four feet of maximum dimension are generated
during grading, or otherwise desired to be placed within an engineered fill, special handling in
accordance with the recommendations below. Rocks greater than four feet should be broken
down or disposed off-site.
7.2 Placement of Fill
Prior to placement of fill material, the geotechnical consultant should inspect the area to receive
fill. After inspection and approval, the exposed ground surface should be scarified to a depth of
6 to 8 inches. The scarified material should be conditioned (i.e. moisture added or air dried by
continued discing) to achieve a moisture content at or slightly above optimum moisture
conditions and compacted to a minimum of 90 percent of the maximum density or as otherwise
recommended in the soils report or by appropriate govemment agencies.
Compacted fill should then be placed in thin horizontal lifts not exceeding eight inches in loose
thickness prior to compaction. Each lift should be moisture conditioned as needed, thoroughly
blended to achieve a consistent moisture content at or slightly above optimum and thoroughly
compacted by mechanical methods to a minimum of 90 percent of laboratory maximum dry
density. Each lift should be treated in a like manner until the desired finished grades are
achieved.
The contractor should have suitable and sufficient mechanical compaction equipment and
watering apparatus on the job site to handle the amount of fill being placed in consideration of
moisture retention properties of the materials and weather conditions.
When placing fill in horizontal lifts adjacent to areas sloping steeper than 5:1 (horizontal:
vertical), horizontal keys and vertical benches should be excavated into the adjacent slope area.
Keying and benching should be sufficient to provide at least six-foot wide benches and a
minimum of four feet of vertical bench height within the firm natural ground, firm bedrock or
engineered compacted fill. No compacted fill should be placed in an area after keying and
benching until the geotechnical consultant has reviewed the area. Material generated by the
benching operation should be moved sufficiently away from the bench area to allow for the
recommended review of the horizontal bench prior to placement of fill.
Within a single fill area where grading procedures dictate two or more separate fills, temporary
slopes (false slopes) may be created. When placing fill adjacent to a false slope, benching should
be conducted in the same manner as above described. At least a 3-foot vertical bench should be
established within the firm core of adjacent approved compacted fill prior to placement of
additional fill. Benching should proceed in at least 3-foot vertical increments until the desired
finished grades are achieved.
Prior to placement of additional compacted fill following an overnight or other grading delay, the
exposed surface or previously compacted fill should be processed by scarification, moisture
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Standard Grading Specifications
conditioning as needed to at or slightly above optimum moisture content, thoroughly blended emd
recompacted to a minimum of 90 percent of laboratory maximum dry density. Where unsuitable
materials exist to depths of greater than one foot, the unsuitable materials should be over-
excavated.
Following a period of flooding, rainfall or overwatering by other means, no additional fill should
be placed until damage assessments have been made and remedial grading performed as
described herein.
Rocks 12 inch in maximum dimension and smaller may be utilized in the compacted fill
provided the fill is placed and thoroughly compacted over and around all rock. No oversize
material should be used within 3 feet of finished pad grade and within 1 foot of other compacted
fill areas. Rocks 12 inches up to four feet maximum dimension should be placed below the
upper 5 feet of any fill and should not be closer than 11 feet to any slope face. These
recommendations could vary as locations of improvements dictate. Where practical, oversized
material should not be placed below areas where stmctures or deep utilities are proposed.
Oversized material should be placed in windrows on a clean, overexcavated or unyielding
compacted fill or firm natural ground surface. Select native or imported granular soil (S.E. 30 or
higher) should be placed and thoroughly flooded over and around all windrowed rock, such that
voids are filled. Windrows of oversized material should be staggered so those successive strata
of oversized material are not in the same vertical plane.
It may be possible to dispose of individual larger rock as field conditions dictate and as
recommended by the geotechnical consultant at the time of placement.
The contractor should assist the geotechnical consultant and/or his representative by digging test
pits for removal determinations and/or for testing compacted fill. The contractor should provide
this work at no additional cost to the owner or contractor's client.
Fill should be tested by the geotechnical consultant for compliance with the recommended
relative compaction and moisture conditions. Field density testing should conform to ASTM
Method of Test D 1556-82, D 2922-81. Tests should be conducted at a minimum of two vertical
feet or 1,000 cubic yards of fill placed. Actual test intervals may vary as field conditions dictate.
Fill found not to be in conformance with the grading recommendations should be removed or
otherwise handled as recommended by the geotechnical consultant.
7.3 Fill Slopes
Unless otherwise recommended by the geotechnical consultant and approved by the regulating
agencies, permanent fill slopes should not be steeper than 2:1 (horizontal: vertical).
Except as specifically recommended in these grading guidelines compacted fill slopes should be
over-built and cut back to grade, exposing the firm, compacted fill inner core. The actual
amount of overbuilding may vary as field conditions dictate. If the desired results are not
achieved, the existing slopes should be overexcavated and reconstmcted under the guidelines of
the geotechnical consultant. The degree of overbuilding shall be increased until the desired
compacted slope surface condition is achieved. Care should be taken by the contractor to
provide thorough mechanical compaction to the outer edge ofthe overbuilt slope surface.
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Standard Grading Specifications
At the discretion of the geotechnical consultant, slope face compaction may be attempted by
conventional construction procedures including backrolling. The procedure must create a firmly
compacted material throughout the entire depth of the slope face to the surface of the previously
compacted firm fill intercore.
During grading operations, care should be taken to extend compactive effort to the outer edge of
the slope. Each lift should extend horizontally to the desired finished slope surface or more as
needed to ultimately established desired grades. Grade during construction should not be
allowed to roll off at the edge of the slope. It may be helpful to elevate slightly the outer edge of
the slope. Slough resulting from the placement of individual lifts should not be allowed to drift
down over previous lifts. At intervals not exceeding four feet in vertical slope height or the
capability of available equipment, whichever is less, fill slopes should be thoroughly dozer
trackrolled.
For pad areas above fill slopes, positive drainage should be established away from the
top-of-slope. This may be accomplished using a berm and pad gradient of at least 2 percent.
Section 8 - Trench Backfill
Utility and/or other excavation of trench backfill should, unless otherwise recommended, be
compacted by mechanical means. Unless otherwise recommended, the degree of compaction
should be a minimum of 90 percent of the laboratory maximum density.
Within slab areas, but outside the influence of foundations, trenches up to one foot wide and two
feet deep may be backfilled with sand and consolidated by jetting, flooding or by mechanical
means. If on-site materials are utilized, they should be wheel-rolled, tamped or otherwise
compacted to a firm condition. For minor interior trenches, density testing may be deleted or
spot testing may be elected if deemed necessary, based on review of backfill operations during
construction.
If utility contractors indicate that it is undesirable to use compaction equipment in close
proximity to a buried conduit, the contractor may elect the utilization of light weight mechanical
compaction equipment and/or shading of the conduit with clean, granular material, which should
be thoroughly jetted in-place above the conduit, prior to initiating mechanical compaction
procedures. Other methods of utility trench compaction may also be appropriate, upon review of
the geotechnical consultant at the time of constmction.
In cases where clean granular materials are proposed for use in lieu of native materials or where
flooding or jetting is proposed, the procedures should be considered subject to review by the
geotechnical consultant. Clean granular backfill and/or bedding are not recommended in slope
areas.
Section 9 - Drainage
Where deemed appropriate by the geotechnical consultant, canyon subdrain systems should be
installed in accordance.
Typical subdrains for compacted fill buttresses, slope stabilization or sidehill masses, should be
installed in accordance with the specifications.
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Standard Grading Specifications
Roof, pad and slope drainage should be directed away from slopes and areas of stmctures to
suitable disposal areas via non-erodible devices (i.e., gutters, downspouts, and concrete swales).
For drainage in extensively landscaped areas near stmctures, (i.e., within four feet) a minimum
of 5 percent gradient away from the stmcture should be maintained. Pad drainage of at least 2
percent should be maintained over the remainder ofthe site.
Drainage patterns established at the time of fine grading should be maintained throughout the life
of the project. Property owners should be made aware that altering drainage patterns could be
detrimental to slope stability and foundation performance.
Section 10 - Slope Maintenance
10.1 - Landscape Plants
To enhance surficial slope stability, slope planting should be accomplished at the completion of
grading. Slope planting should consist of deep-rooting vegetation requiring little watering.
Plants native to the southem Califomia area and plants relative to native plants are generally
desirable. Plants native to other semi-arid and arid areas may also be appropriate. A Landscape
Architect should be the best party to consult regarding actual types of plants and planting
configuration.
10.2 - Irrigation
Irrigation pipes should be anchored to slope faces, not placed in trenches excavated into slope
faces.
Slope irtigation should be minimized. If automatic timing devices are utilized on irtigation
systems, provisions should be made for intertupting normal irrigation during periods of rainfall.
10.3 - Repair
As a precautionary measure, plastic sheeting should be readily available, or kept on hand, to
protect all slope areas from saturation by periods of heavy or prolonged rainfall. This measure is
strongly recommended, beginning with the period prior to landscape planting.
If slope failures occur, the geotechnical consultant should be contacted for a field review of site
conditions and development of recommendations for evaluation and repair.
If slope failures occur as a result of exposure to period of heavy rainfall, the failure areas and
curtently unaffected areas should be covered with plastic sheeting to protect against additional
saturation.
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