HomeMy WebLinkAboutPD 2021-0040; 786 PALM AVENUE; LIMITED GEOTECHNICAL EVALUATION; 2020-08-14
LIMITED GEOTECHNICAL EVALUATION
FOR
786 PALM AVENUE
CARLSBAD, CALIFORNIA 92008
PREPARED FOR
AB 3
2834 LA MIRADA Drive, Suite E
VISTA, CALIFORNIA 92081
PREPARED BY
GEOTEK, INC.
1384 POINSETTIA AVENUE
VISTA, CALIFORNIA 92081
PROJECT NO. 3653-SD AUGUST 14, 2020
August 14, 2020
Project No. 3653-SD
AB 3
C/O P&E coast Construction
2834 La Mirada Drive, Suite E
Vista, California 92081
Subject: Limited Geotechnical Evaluation
Proposed Residence with ADU
786 Palm Avenue APN 214-39-011
Carlsbad, California 92008
We are pleased to provide herein the results of our limited geotechnical evaluation for
the proposed Residence and Accessory Dwelling Unit (ADU) on the subject site located
at 786 Palm Avenue, Carlsbad, California 92008. This report presents the results of our
limited evaluation, discussion of our findings and recommendations. In our opinion,
planned site development appears feasible from a geotechnical viewpoint provided the
recommendations presented herein are incorporated into the design and construction. No
significant grade changes are planned.
The opportunity to be of service is sincerely appreciated. If you should have any questions,
please do not hesitate to call our office.
Respectfully Submitted,
GeoTek, Inc.
Timothy E. Metcalfe, CEG 1142
Principal Geologist
Chris E Lillback RCE 35007
Senior Project Engineer
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad, California 92008 Page i
TABLE OF CONTENTS
1. PURPOSE AND SCOPE OF SERVICES .................................................................................................... 1
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT .................................................................... 1
2.1 SITE DESCRIPTION .................................................................................................................................... 1
2.2 PROPOSED DEVELOPMENT ........................................................................................................................ 1
3. FIELD STUDY AND LABORATORY TESTING ...................................................................................... 2
3.1 SITE WORK ............................................................................................................................................... 2
3.2 LABORATORY TESTING ............................................................................................................................ 2
4. GEOLOGIC AND SOILS CONDITIONS ................................................................................................... 2
4.1 REGIONAL SETTING .................................................................................................................................. 2
4.2 GENERAL SOIL CONDITIONS ..................................................................................................................... 3
4.3 SURFACE AND GROUND WATER ................................................................................................................ 3
4.3.1 Surface Water ................................................................................................................................. 3
4.3.2 Groundwater .................................................................................................................................. 3
4.3.3 Infiltration ...................................................................................................................................... 3
4.4 FAULTING AND SEISMICITY ...................................................................................................................... 3
4.4.1 Seismic Design Parameters ............................................................................................................ 3
4.5 OTHER SEISMIC HAZARDS ........................................................................................................................ 4
5. CONCLUSIONS AND RECOMMENDATIONS ........................................................................................ 4
5.1 GENERAL .................................................................................................................................................. 4
5.2 EARTHWORK CONSIDERATIONS................................................................................................................ 5
5.2.1 Site Clearing and Preparation ....................................................................................................... 5
5.2.2 Engineered Fills ............................................................................................................................. 5
5.2.3 Removal Recommendations ........................................................................................................... 5
5.2.4 Removal Bottoms............................................................................................................................ 5
5.2.5 Excavation Characteristics ............................................................................................................ 6
5.2.6 Shrinkage and Bulking ................................................................................................................... 6
5.2.7 Trench Excavations and Backfill.................................................................................................... 6
5.3 DESIGN RECOMMENDATIONS ................................................................................................................... 7
5.3.1 Foundation Design Criteria ........................................................................................................... 7
5.3.2 Miscellaneous Foundation Recommendations ............................................................................... 8
5.3.3 Moisture and Vapor Retarding System .......................................................................................... 8
5.3.4 Concrete Construction ................................................................................................................... 9
5.4 POST CONSTRUCTION CONSIDERATIONS ................................................................................................ 10
5.4.1 Landscape Maintenance and Planting ......................................................................................... 10
5.4.2 Drainage ...................................................................................................................................... 10
5.5 CONSTRUCTION OBSERVATIONS ............................................................................................................. 10
6. INTENT ......................................................................................................................................................... 11
7. LIMITATIONS ............................................................................................................................................. 11
8. SELECTED REFERENCES ....................................................................................................................... 12
ENCLOSURES Figure 1 – Site Location Map
Figure 2 – Auger Location Map
Figure 2 – Regional Geologic Map
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 1
1. PURPOSE AND SCOPE OF SERVICES
The purpose of the limited study was to evaluate the geotechnical conditions at the site relative
to the anticipated site improvements. Services provided for this study included the following:
➢ Research and review of readily available geologic data and general information pertinent to
the site,
➢ Review of data in our files,
➢ On site observations, excavation of two manual auger holes (one on site and one on the
adjacent parcel to the east), obtaining one sample for laboratory analysis,
➢ Review of site seismicity,
➢ Geologic and geotechnical analyses of the data obtained,
➢ Compilation of this geotechnical report which presents our findings, conclusions, and
recommendations for construction of the proposed site improvements.
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
2.1 SITE DESCRIPTION
The subject site is located at 786 Palm Avenue, (Palm) Carlsbad, California 92008 (see Figure
1). The roughly 3450 square feet (sf) site is APN 214-39-011. It lies on the northwest side of
Palm, west of Jefferson Street and adjacent to an alley on the west. The site is currently occupied
by a one-story residence, apparently constructed in the 1950’s based on review of aerial
photograph available online. Prior to that it appears that the site was undeveloped with possible
agricultural use in the 1930’s and 1940’s. The site is fairly flat. It appears to drain toward the alley
and Palm.
2.2 PROPOSED DEVELOPMENT
Based on Plans provided to Mr. Joe Barbano and discussions, we understand that the planned
construction consists a two story residence with an accessory dwelling unit. The existing
structure will be demolished. No significant grading is planned as the site is currently fairly level.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 2
3. FIELD STUDY AND LABORATORY TESTING
3.1 SITE WORK
A limited field study was performed excavating two manual auger holes to assess shallow
subsurface conditions and obtain a sample of soil for review laboratory testing. One of the
borings was done on the adjacent site.
Based on our test excavations, regional mapping, and experience in the area, the site is underlain
by old paralic deposits. Locally these are very loose near the surface and become relatively more
dense at a depth of about 3 to 3½ ft. As encountered the material is a slightly silty Sand.
Observed moisture contents were typically considered to be slightly moist. Auger Locations and
Logs are presented on Figure 2.
3.2 LABORATORY TESTING
No specific laboratory testing was considered necessary as Visual and tactical assessment
indicated that the soils are slightly silty sand and non-plastic. This is consistent with prior testing
but this firm from prior work on nearby sites. Testing in the area on paralic deposits also found
that water-soluble sulfate content fall into the negligible range per Table 4.2.1 of ACI 318.
4. GEOLOGIC AND SOILS CONDITIONS
4.1 REGIONAL SETTING
The subject site is situated within the coastal section of the Peninsular Ranges Geomorphic
Province of California. The Peninsular Ranges province occupies the southwestern portion of
the state of California. The Peninsular Ranges contain the deeply eroded remnants of a single
continuous volcano-plutonic arc that formed during the Mesozoic. The Peninsular Ranges’
dominant structural features are northwestward trending fault blocks. The Peninsular Ranges
province is bounded by the Transverse Ranges Province to the north, the Colorado Desert
Province to the east, Mexico to the south, and the Pacific Ocean to the west. Included within
the province are the offshore islands of Santa Catalina, San Clemente, and Santa Barbara. Major
mountain ranges within the province include the San Jacinto, Santa Ana, Santa Rosa, Agua Tibia,
and Laguna Mountains. The highest elevation is found at San Jacinto Peak (10,805-feet) in the
San Jacinto Mountains. Summit elevations generally decrease to the west. Slopes in the western
portion of the province are gentler, similar to the Sierra Nevada. Drainage is generally provided
by the San Diego, San Dieguito, San Luis Rey, Santa Margarita, Santa Ana, and San Jacinto Rivers.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 3
4.2 GENERAL SOIL CONDITIONS
Regional geologic mapping suggests the area is underlain by very old paralic deposits however
based on the exposed conditions, site reconnaissance, review of published geologic maps, and
our general knowledge of the area, paralic deposits were encountered in the auger holes overlain
by minor landscape fill. Figure 2 is a Regional Geologic Map.
4.3 SURFACE AND GROUND WATER
4.3.1 Surface Water
If encountered during the construction, surface water on this site is likely the result of onsite
precipitation. Proper site drainage to minimize ponding of water should be provided and is under
the purview of the Civil Engineer.
4.3.2 Groundwater
There is no evidence that near surface groundwater is present on the site although local
perched water could be encountered especially seasonally.
4.3.3 Infiltration
We understand that while permeable pavements may be incorporated in the design, no specific
infiltration is planned for the site so that no testing has been done.
4.4 FAULTING AND SEISMICITY
The geologic structure of the entire southern California area is dominated mainly by northwest-
trending faults associated with the San Andreas system. The site is in a seismically active region.
No active or potentially active fault is known to exist at this site; the site is neither situated
within an “Alquist-Priolo” Earthquake Fault Zone, nor within a State of California Seismic Hazards
Zone. No local agencies have identified a hazard zone for the site.
4.4.1 Seismic Design Parameters
The site is located at 786 Palm Avenue. Site spectral accelerations (Ss and S1), for 0.2 and 1.0
second periods for a Class “C” site, were determined from the web site seismismaps.org,
developed by SEAOC and OSHPD that uses the USGS web services. A Class “C” is considered
appropriate based on the paralic deposits. The results are presented in the following table:
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 4
SITE SEISMIC PARAMETERS
Mapped 0.2 sec Period Spectral Acceleration, Ss 1.073
Mapped 1.0 sec Period Spectral Acceleration, S1 0.388
Site Coefficient, Fa 1.2
Site Coefficient, Fv 1.5
Maximum Considered Earthquake Spectral
Response Acceleration for 0.2 Second, SMS 1.287
Maximum Considered Earthquake Spectral
Response Acceleration for 1.0 Second, SM1 .582
5% Damped Design Spectral Response
Acceleration Parameter at 0.2 Second, SDS 0.858
5% Damped Design Spectral Response
Acceleration Parameter at 1 second, SD1 0.358
Site Modified Ground Acceleration, PGAM 0.568
4.5 OTHER SEISMIC HAZARDS
The site is in an area of gently sloping terrain underlain by paralic deposits and Santiago Formation
at depth. No evidence of ancient landslides or slope instabilities at this site was observed during
our study or through general research. No mapped landslides are in the immediate area of the
site. Thus, the potential for landslides is considered negligible.
The potential for secondary seismic hazards of seiche and tsunami are considered to be negligible
due to site elevation (~126 feet MSL) and distance from an open body of water.
Based on the relatively dense nature of the near surface units and the lack of shallow consistent
groundwater table, the potential for liquefaction resulting in significant dynamic settlement is
considered to be negligible.
5. CONCLUSIONS AND RECOMMENDATIONS
5.1 GENERAL
The proposed construction appears feasible from a geotechnical viewpoint provided that the
following recommendations are incorporated into the design and construction phases of
development. Recommendations are provided slab-on-ground type construction.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 5
5.2 EARTHWORK CONSIDERATIONS
It is our understanding that no significant grade changes are proposed. Any earthwork and
grading that might be performed should be in accordance with the applicable grading ordinances
of the City of Carlsbad, the 2019 California Building Code (CBC), and recommendations
contained in this report.
5.2.1 Site Clearing and Preparation
In areas of planned grading or improvements, the site should be cleared of existing
improvements, grass and any other vegetation; roots, trash and debris, should be properly
disposed of offsite. Cavities resulting from demolition and site clearing, tree removal, etc. should
be observed by the project geotechnical consultant prior to replacement with engineered fill
materials. The onsite soils, including the upper twelve (12) inches of soil, are considered suitable
for reuse as engineered fill provided, they are free from vegetation, debris and other deleterious
material.
The contractor should take all precautions deemed necessary during site grading and trenching
to maintain adequate safety measures and working conditions.
5.2.2 Engineered Fills
Engineered fill materials should be moisture conditioned to optimum moisture content or slightly
above and compacted in horizontal lifts not exceeding 8” in loose thickness to a minimum relative
compaction of 90% as determined in accordance with laboratory test procedure ASTM D 1557.
5.2.3 Removal Recommendations
Removal and recompaction of the upper loose paralic deposits are recommended. This is
anticipated to be 3 to 3½ from existing grade. Removals should minimally include the building
envelop and approximate 5 feet outside the perimeter. In areas of non-structural improvement
approximately 2 feet of removal should be completed. During removals workers should be aware
that there is a possibility that an abandon septic system could be present. If encountered the
system should be completely removed and backfilled with properly compacted fill. If a deep
seepage pit is present optional recommendation may be offered.
5.2.4 Removal Bottoms
If applicable the bottom of all removals should be scarified to a minimum depth of eight (8)
inches, brought to at or above optimum moisture content, and then compacted to minimum
project standards prior to fill placement. The remedial excavation bottoms of should be observed
by a GeoTek representative prior to scarification. The resultant voids from remedial
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 6
grading/overexcavation should be filled with materials placed in accordance with Section 5.2.2 of
this report.
5.2.5 Excavation Characteristics
Excavation in the onsite soil materials is expected to be relatively easy using light to medium
duty equipment in good operating condition.
5.2.6 Shrinkage and Bulking
Volume loss as the result of demolition and compaction of loose soil is anticipated. The
recompacted soils will likely experience a volume decrease of 10 to 15%. It may be prudent to
considered bringing the building envelop to grade and using the trench spoil to complete as much
of the perimeter grading as possible. This should limit the need for import and potential export.
5.2.7 Trench Excavations and Backfill
In general, temporary excavations within the onsite materials should be stable at 1:1 (H:V)
inclinations for cuts less than 5 feet in height. Where this condition occurs, the trenches may
need to be sloped back at flatter inclinations and the slope face cleaned of loose materials and
properly protected. Onsite soils generally classify as “Type C” soils per OSHA guidelines.
Trench excavations should conform to Cal-OSHA regulations. The contractor should have a
competent person, per OSHA requirements, on site during construction to observe conditions
and to make the appropriate recommendations.
Utility trench backfill should be compacted to at least 90% relative compaction (as determined
per ASTM D 1557). Under-slab trenches should also be compacted to project specifications.
Where applicable, based on jurisdictional requirements, the top 12 inches of backfill below
subgrade for road pavements should be compacted to at least 95 percent relative compaction.
Onsite materials may not be suitable for use as bedding material, but will be suitable as backfill
provided particles larger than 3± inches are removed.
Compaction should be achieved with a mechanical compaction device. Ponding or jetting of
trench backfill is not recommended. If backfill soils have dried out, they should be thoroughly
moisture conditioned prior to placement in trenches.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 7
5.3 DESIGN RECOMMENDATIONS
5.3.1 Foundation Design Criteria
Foundation design criteria for a conventional foundation system, in general conformance with
the 2019 CBC, are presented below.
Based on the non-plastic nature of onsite soils may be classified as “very low” expansive soils
(EI<20). Below is typical design criteria based on a “very low” expansion potential. These
minimal recommendations and are not intended to supersede the design by the structural
engineer.
Shallow foundation elements, if used to support the proposed structures, perimeter walls, and
other improvements should be founded either entirely in engineered fill or entirely in competent
bedrock. Based on the hand auger holes structures/improvements should be founded below a
depth 18 inches although the western addition may require deepened footings to encounter the
bedrock.
A summary of our foundation design recommendations for one and two-story structures are
presented below:
MINIMUM DESIGN REQUIREMENTS
DESIGN PARAMETER 0≤EI≤20
Foundation Depth or Minimum Perimeter Beam
Depth (below lowest adjacent grade)
One story - 12”
Two Story -18”
Foundation Width (Inches) Per CBC minimum
Minimum Slab Thickness (inches) 4 (actual)
Minimum Slab Reinforcing No. 3 rebar
18” on-center, placed in the middle 1/3 of the slab
Minimum Footing Reinforcement Two (4) No. 4 Reinforcing Bars-
One (1) top and one (1) bottom
Presaturation of Subgrade Soil
(Percent of Optimum/Depth in Inches) 100% / 12 inches
It should be noted that the above recommendations are based on soil support characteristics
only. The structural engineer should design the slab and beam reinforcement based on actual
loading conditions.
The following criteria for design of foundations should be implemented into design:
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 8
5.3.1.1 Bearing Capacity
For footings placed in paralic deposits fill or engineered fill performed as recommended in
Section 5.2, a net allowable bearing capacity of 2,000 pounds per square foot (psf) may be used
for design of continuous and perimeter footings 12 inches deep (below lowest adjacent grade)
and 12 inches wide, and pad footings 24 inches square and 18 inches deep. This value may be
increased by 200 pounds per square foot for each additional 12 inches in depth and 100 pounds
per square foot for each additional 12 inches in width to a maximum value of 3000 psf.
Additionally, an increase of one-third may be applied when considering short-term live loads (e.g.
seismic and wind loads).
5.3.1.2 Design Settlement Value
Based on our evaluation, structural foundations may be designed to withstand a total settlement
of approximately ¾- inch and maximum differential settlement of one-half of the total settlement.
5.3.1.3 Lateral Resistance
For footings founded on engineered fill materials the passive earth pressure may be computed
as an equivalent fluid having a density of 250 psf per foot of depth, to a maximum earth pressure
of 2,500 psf. A coefficient of friction between soil and concrete of 0.30 may be used with dead
load forces. When combining passive pressure and frictional resistance, the passive pressure
component should be reduced by one-third.
5.3.2 Miscellaneous Foundation Recommendations
A grade beam, 12 inches wide by 18 inches deep (minimum), should be utilized across large
openings. The base of the grade beam should be at the same elevation or deeper than the
bottom of the adjoining footings.
To minimize moisture penetration beneath the slab on grade areas, utility trenches should be
backfilled with engineered fill, lean concrete or concrete slurry where they intercept the
perimeter footing or thickened slab edge.
Soils from the footing excavations should not be placed in the slab-on-grade areas unless properly
compacted and tested. The excavations should be free of loose/sloughed materials and be neatly
trimmed at the time of concrete placement.
5.3.3 Moisture and Vapor Retarding System
A moisture and vapor retarding system should be placed below slabs-on-grade where moisture
migration through the slab is undesirable. Guidelines for these systems are provided in the 2016
California Green Building Standards Code (CALGreen) Section 4.505.2 and the 2019 CBC
Section 1910.1.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 9
It should be realized that the effectiveness of the vapor retarding membrane can be adversely
impacted as the result of construction related punctures (e.g. stake penetrations, tears,
punctures from walking on the aggregate layer, etc.). These occurrences should be limited as
much as possible during construction. Thicker membranes are generally more resistant to
accidental puncture than thinner ones. Products specifically designed for use as moisture/vapor
retarders may also be more puncture resistant.
Moisture and vapor retarding systems are intended to provide a certain level of resistance to
vapor and moisture transmission through the concrete, but do not eliminate it. The acceptable
level of moisture transmission through the slab is to a large extent based on the type of flooring
used and atmospheric conditions. Ultimately, the vapor retarding system should be comprised
of suitable elements to limit migration of water and reduce transmission of water vapor through
the slab to acceptable levels. The selected elements should have suitable properties (i.e.
thickness, composition, strength, and permeance) to achieve the desired performance level.
Consideration should be given to consulting with an individual possessing specific expertise in
this area for additional evaluation.
5.3.4 Concrete Construction
5.3.4.1 General
Concrete construction should follow the CBC and ACI guidelines regarding design, mix
placement and curing of the concrete. If desired, GeoTek can provide quality control testing of
the concrete during construction.
5.3.4.2 Concrete Soluble Sulfate
Results of the from nearby sites have indicated “not applicable” (i.e. negligible) conditions per
Table 4.2.1 of ACI 318. Accordingly, no special concrete mix design provisions with regard to
minimum compressive strength, cement type, or water/cement ratio are required to resist
sulfate attack.
5.3.4.3 Concrete Flatwork
Exterior concrete flatwork may be poured directly on compacted native soils. Driveways should
be a minimum of 5 inches thick and reinforced with should a minimum of No 3 reinforcing bars
place 18 inches on center in two directions. Other flatwork should be a minimum of 4 inches
thick and maybe be reinforced with 6x6 No 6 WWM or No. 3 reinforcing bars place 24 inches
on center in two directions. Control joints should be placed at approximately 24 times the
thickness of the slab.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 10
5.4 POST CONSTRUCTION CONSIDERATIONS
5.4.1 Landscape Maintenance and Planting
Water has been shown to weaken the inherent strength of soil. Positive surface drainage away
from graded slopes should be maintained and only the amount of irrigation necessary to sustain
plant life should be provided for planted slopes. Controlling surface drainage and runoff, and
maintaining a suitable vegetation cover can minimize erosion. Plants selected for landscaping
should be lightweight, deep-rooted types that require little water and are capable of surviving
the prevailing climate.
Overwatering should be avoided. The soils should be maintained in a solid to semi-solid state
as defined by the materials Atterberg Limits. Care should be taken when adding soil amendments
to avoid excessive watering. Leaching as a method of soil preparation prior to planting is not
recommended.
5.4.2 Drainage
The need to maintain proper surface drainage and subsurface systems cannot be overly
emphasized. Positive site drainage should be maintained at all times. Drainage should not flow
uncontrolled down any descending slope. Water should be directed away from foundations and
not allowed to pond or seep into the ground. Drainage should be directed toward approved
area(s) and not be blocked by other improvements.
5.5 CONSTRUCTION OBSERVATIONS
GeoTek representatives should be present during site grading and foundation construction to
check for proper implementation of the geotechnical recommendations. These representatives
should perform at least the following duties:
• Observe site clearing and grubbing operations for proper removal of unsuitable materials.
• Observe and test bottom of removals prior to fill placement.
• Evaluate the suitability of on-site and import materials for fill placement, and collect soil
samples for laboratory testing where necessary.
• Observe the fill for uniformity during placement including utility trenches. Also, test the fill
for field density and relative compaction.
• Observe and probe foundation materials to confirm suitability of bearing materials.
If requested, GeoTek will provide a construction observation and compaction report to comply
with the requirements of the governmental agencies having jurisdiction over the project for the
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue, Carlsbad Page 11
site. We recommend that these agencies be notified prior to commencement of construction
so that necessary construction permits can be obtained.
6. INTENT
It is the intent of this report to aid in the preliminary design for the proposed improvements.
Implementation of the advice presented in Section 5 of this report is intended to reduce risk
associated with construction projects. The professional opinions and geotechnical advice
contained in this report are not intended to imply total performance of the project or guarantee
that unusual or variable conditions will not be discovered during or after construction.
The scope of our evaluation is limited to observation of existing excavation and near surface
condition. This evaluation does not and should in no way be construed to encompass any areas
beyond the specific area of proposed improvements as indicated to us by the client. Further, no
evaluation of any existing site improvements is included. The scope is based on our
understanding of the project and the client’s needs, and geotechnical engineering standards
normally used on similar projects in this region.
7. LIMITATIONS
The materials observed on the project site appear to be representative of the area; however,
soil and bedrock materials vary in character between excavations and natural outcrops or
conditions exposed during site construction. Site conditions may vary due to seasonal changes
or other factors. GeoTek, Inc. assumes no responsibility or liability for work, testing or
recommendations performed or provided by others.
Since our recommendations are based on the site conditions observed and encountered, and
laboratory testing, our conclusions and recommendations are professional opinions that are
limited to the extent of the available data. Observations during construction are important to
allow for any change in recommendations found to be warranted. These opinions have been
derived in accordance with current standards of practice and no warranty is expressed or
implied. Standards of practice are subject to change with time.
AB 3 Project No. 3653-SD
Limited Geotechnical Evaluation August 14, 2020
786 Palm Avenue Page 12
8. SELECTED REFERENCES
ASTM, 2011, “Soil and Rock: American Society for Testing and Materials,” vol. 4.08 for ASTM
test methods D-420 to D-5876,; and vol. 4.09 for ASTM test method D-5877 to latest.
California Code of Regulations, Title 24, 2019 “California Residential Building Code,” 3 volumes.
California Division of Mines and Geology (CDMG), 2008, “Guidelines for Evaluating and
Mitigating Seismic Hazards in California,” Special Publication 117A
GeoTek, Inc., In-house proprietary information.
Seismic Design Values for Buildings (http://seismic.org).
Geologic Map of the Oceanside 30' X 60' Quadrangle, California, Compiled by Michael P.
Kennedy and Siang S. Tan, 2005 Digital Preparation by Kelly R. Bovard1, Rachel M.
Alvarez1and Michael J. Watson1 U.S. Geological Survey, Department of Earth Sciences,
University of California, Riverside
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Figure 1
Site Location Map
786 Palm Ave –Lot 11
Carlsbad, California
August 2020
Not to scale From:https://sdgis.sandag.org/
SITE
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Figure 2
Auger Location Map
AB-3 Palm Avenue (Lot 11)
Carlsbad, California
August 2020
HA-1
LOT 10
Scale in Feet
0 50 100
HA-2
HA-1
LOT 11
N.A.P
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
Figure 3
Regional Geologic Map
AB3 -Palm Avenue
Carlsbad, California
August 2020
Not to scale
From: Geologic Map Of The Oceanside 30' X 60' Quadrangle,
California” Compiled by Michael P. Kennedy and Siang S. Tan,2005, published by. U.S. Geological Survey.
SITE