HomeMy WebLinkAboutCT 14-07; BEACHWALK AT ROOSEVELT; UPDATED PRELIMINARY GEOTECHNICAL EVALUATION; 2016-04-15CeoTek, Inc.
1184 Poinseufa Av1:nue, Suite A Vim, CA 91081-BS0S
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Vesta Pacific Development
1818 Second Avenue
San Diego, California 920 I I
Attention:
Subject:
Mr. Geoff McComic
Updated Preliminary Geotechnical Evaluation
Beachwalk at Roosevelt: CT 14-07
2685, 2687 & 2715 Roosevelt Street
Carlsbad, California
Dear Mr. McComic:
LA
April 15, 2016
Project No. 3447-SD3
DEC O 5 2017
We are pleased to provide herewith this updated preliminary geotechnical evaluation for the
subject site located in Carlsbad, California. This report responds to comments by the City of
Carlsbad contracted reviewer regarding our July 14, 2014 report for the project and presents
results of our 2014 evaluation, discussion of our findings, and provides geotechnical
recommendations for foundation design and construction. As such this report may be used
without reference to the earlier report. In our opinion, site development appears feasible
from a geotechnical viewpoint provided that the recommendations included herein are
incorporated into the design and construction phases of site development.
Respectfully submitted,
GeoTek, Inc.
Principal Geologist
Distribution: (5) Addressee
~Pim
RCE 35007, Exp. 06/30/ 17
Project Engineer
GEOTECHNICAL I ENVIRONMENTAL I MATERIALS
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
TABLE OF CONTENTS
Project No. 3447-SO3
April IS, 2016
Page i
I. PURPOSE AND SCOPE OF SERVICES ............................................................................................. I
2. CITY REVIEW COMMENTS ............................................................................................................... I
3. SITE DESCRIPTION AND PROPOSED DEVELOPMENT .............................................................. 2
3.1 SITE DESCRIPTION ................................................................................................................................................................... 2
3.2 PROPOSED DEVELOPMENT ..................................................................................................................................................... 2
4. FIELD EXPLORATION AND LABORATORY TESTING ................................................................ 3
4.1 FIELD EXPLORATION ............................................................................................................................................................... 3
4.2 LABORATORY TESTING .......................................................................................................................................................... 3
5. GEOLOGIC AND SOILS CONDITIONS ........................................................................................... 4
5.1 REGIONAL SETTING ................................................................................................................................................................ 4
5.2 GENERAL SOIL CONDITIONS ................................................................................................................................................. 5
5.3 SURFACE AND GROUNDWATER ........................................................................................................................................... 6
5.3. I Surface Water ................................................................................................................................................................................. 6
5.3.2 Groundwater .................................................................................................................................................................................... 6
5.4 FAULTING AND SEISMICITY .................................................................................................................................................... 6
5.4. I Seismic Design Parameters ......................................................................................................................................................... 6
5.5 LIQUEFACTION AND SEISMICALLY INDUCED SETTLEMENT ................................................................................................ ?
5.6 OTHER SEISMIC HAZARDS ..................................................................................................................................................... 8
6. CONCLUSIONS AND RECOMMENDATIONS ................................................................................ 8
6.1 GENERAL······························· ................................................................................................................................................... 8
6.2 EARTHWORK CONSIDERATIONS .......................................................................................................................................... 8
6.2. / Site Clearing ..................................................................................................................................................................................... 8
6.2.2 Fills ....................................................................................................................................................................................................... 9
6.2.3 Removals ........................................................................................................................................................................................... 9
6.2.4 Excavation Characteristics ........................................................................................................................................................... 9
6.2.5 Shrinkage, Bulking, and Subsidence ....................................................................................................................................... 10
6.2.6 Import Soil ...................................................................................................................................................................................... 10
6.3 DESIGN RECOMMENDATIONS ............................................................................................................................................ I 0
6.3. I Foundation Design Criteria ........................................................................................................................................................ I 0
6.3.2 Unders/ab Compaction Recommendations .......................................................................................................................... 12
6.3.3 Moisture and Vapor Retarding System ................................................................................................................................. 12
6.3.4 Settlement ....................................................................................................................................................................................... 13
6.3.5 Foundation Set Backs .................................................................................................................................................................. 13
6.3.6 Soil Corrosivity ................................................................................................................................................................................ 14
6.3. 7 Soil Sulfate Content ..................................................................................................................................................................... 14
6.4 RETAINING WALL DESIGN AND CONSTRUCTION .......................................................................................................... 14
6.4. I General Design Criteria .............................................................................................................................................................. 14
6.4.2 Cantilevered Walls ....................................................................................................................................................................... 15
6.4.3 Wall Backfill and Drainage ....................................................................................................................................................... 15
6.4.4 Restrained Retaining Walls ....................................................................................................................................................... 16
6.5 BIORETENTION .................................................................................................................................................................... 16
6.6 PAVEMENTDESIGN ............................................................................................................................................................... 16
GEOTEK
Vesta Pacific Development
Updated Pre~iminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
TABLE OF CONTENTS
Project No. 3447-SD3
April I 5, 2016
Page ii
6.7 FLATWORK ........................................................................................................................................................................... 17
6.8 POST CONSTRUCTION CONSIDERATIONS ....................................................................................................................... 17
6.8. I Landscape Maintenance and Planting ................................................................................................................................... 17
6.8.2 Drainage .......................................................................................................................................................................................... 18
6.9 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS ................................................................................................... 18
7. INTENT ............................................................................................................................................... 18
8. LIMITATIONS .................................................................................................................................... 19
9. SELECTED REFERENCES ................................................................................................................. 20
GRADING GUIDELINES ............................................................................................................................ 0
CITY REVIEW COMMENTS ..................................................................................................................... I
ENCLOSURES
Figure I -Site Location Map
Figure 2 -Site Explorations Map
Logs of Exploratory Excavations
Figure 3 -Regional Geologic Map
Appendix A -Grading Guidelines
Appendix B -City Review Comments
GEO TE K
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
1. PURPOSE AND SCOPE OF SERVICES
Project No. 3447-SO3
April 15, 2016
Page I
The purpose of this report is to update our prior report based on comments provided by the
City's reviewer. This report contains all data from our referenced report and as such may be
used without reference to it. Our initial study was to evaluate the geotechnical conditions in
the area of proposed construction. Services provided relative to this study included the
following:
► Research and review of available geologic data and general information pertinent to the
site,
► Site exploration consisting of the excavation, logging, and sampling of six (6) exploratory
borings,
► Laboratory testing of soil samples collected during the field investigation,
► Review and evaluation of site seismicity,
► Geologic and engineering analysis of data obtained,
► Review and response to the review comments by the City's contract reviewer, and
► Compilation of this geotechnical report which presents our findings, conclusions, and
recommendations for site development.
2. CITY REVIEW COMMENTS
We were provided with a copy of review comments which as we understand were made by
the City of Carlsbad consultant Michael Baker and Associates. The comments are attached
hereto as Appendix B. Below are specific responses to the comments as appropriate.
I) On the cover sheet of our report there are several hand written comments including
the following:
a. Notes to revise the project report title to include the current project name,
tract number and additional address. These items are addressed in this report.
b. Note to "Add Seal and Signature to Cover Sheet". We sign and stamp
preliminary reports on the introductory letter which immediately follows the
report cover page. We are unaware of any code provision that suggests or
requires that the "Cover Sheet" of the report be signed .and stamped. In our
experience it is not a standard in the industry to do this, Further, we checked
reports in our files from five (5) other geotechnical consultants practicing in San
Diego County and prepared within the last few years, none of whom do so.
Perhaps this is a personal or corporate preference of the reviewer, it is not ours.
CEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-5D3
April 15, 2016
Page 2
This is a purely stylistic comment with no technical merit. We do not intend to
do this.
c. Note to provide preliminary pavement design recommendations, these are
provided in Section 6.6 on page 16 of this report
d. Note to provide recommendations regarding lining of infiltration/detention
systems adjacent to building and wall foundations. This is addressed in Section
6.3.5.2 on page 13 and Section 6.5 on page 16.
2) On the cover letter which was signed and stamped by our Engineer and Geologist for
the project it was again noted to modify the site address. This has been done.
3) There are two notes on Page I of the report:
a. It was again noted in two locations to modify the site address.
b. It was noted to modify the page numbering style to "Page X of Y with "Typ"
indicated. We assume "Typ" is meant to indicate that the reviewer feels that
format is typical in the industry. W e again checked reports in our files from five
(5) other consultants prepared within the last few years. One of the five uses a
Page X of Y, three use the format that we do and one uses text rather than
numeric format. This small but random sampling suggests the format we use is
typical. This is a purely stylistic comment with no technical merit, we have not
modified our page numbering style.
3. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
3.1 SITE DESCRIPTION
The site is located at 2685, 2687 and 2715 Roosevelt Street, Carlsbad, California, 92008 (see
Figure I -Site Location Map). The property appears to be rectangular elongated east to west
(perpendicular to Roosevelt). It consists of approximately 30,000 square feet of relative flat
lying terrain. The site is currently occupied by several single-and multi-family residential
buildings. There are two driveway accesses, one servicing approximately the southern third of
the site and the second servicing the north portion of the site. The site is rather, flat sloping
generally to the southwest with about 2 feet of fall. Surface drainage on the site appears to be
directed to the west.
The subject site is bounded by older developed sites both residential and commercial.
3.2 PROPOSED DEVELOPMENT
An undated "Conceptual Grades and Drainage Plan" prepared by Pasco Laret Suiter &
Associates (PSL&A) was provided for our use in preparing our 2014 report. Additionally, we
have reviewed the "Grading Plans for Beachwalk at Roosevelt" by PSL&A dated November 30,
Jl_
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-S03
April I 5, 2016
Page 3
2015 in preparing this report. The Grading Plan indicates 16 multi-family residential units are
planned for the site. Grading will elevate much of the site. Drainage directed to the planned
bioretention /detention basins along Roosevelt Street via a system of private storm drains. The
plan indicates grading quantities include 1800 cubic yards of import soil, shrinkage of the
remedial will likely increase this quantity by an additional 800(+) cubic yards .. This equate to
an average of about 2.2 feet of import fill across the site. Retaining walls will be needed to
achieve grades except along Roosevelt. The walls vary up to approximately five (5) feet high
We anticipate that conventionally reinforced slab-on-grade with spread and continuous wall
footings would be used to support the relatively lightweight framed structure. We understand
the structures will consist of garages at ground level with two (2) floors of living space above.
Structural loads are anticipated to be typical for this type of construction, with wall loads not
exceeding 3000 pounds per lineal foot and isolated columns loads not exceeding 30 kips.
If site development differs from that described above, the recommendations included in this
report should be subject to further review and evaluation.
4. FIELD EXPLORATION AND LABORATORY TESTING
4.1 FIELD EXPLORATION
Field exploration was conducted on April 23, 2014 and June 13, 2014 and consisted of
excavating five (5) exploratory borings with a manual auger to a maximum depth of
approximately 7.5 feet. Representatives from our fi rm logged the excavations and collected
samples for use in the laboratory testing. The logs of exploratory borings are enclosed and the
approximate boring locations are shown on Figure 2 -Site Explorations Map.
4.2 LABO RA TORY TESTING
Laboratory testing was performed on selected soil samples collected during the field
exploration. The purpose of the laboratory testing was to confirm the field classification of the
soil materials encountered and to evaluate their physical properties for use in the engineering
design and analysis. Results of the laboratory testing program, along with a brief description
and relevant information regarding testing procedures are presented below.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Expansion Index
Project No. 3447-SO3
April I 5, 2016
Page 4
Expansion Index (El) testing was performed on two soil samples. Testing was performed in
general accordance with ASTM Test Method D 4829. An El of 25 was determined for a
samples from 84 at 3 feet and an El of I 00 was determined for a sample from Bring 83 at 0 to
2 feet which indicates a low to high expansion potential of existing site soils.
Moisture-Density Relations
Laboratory testing was performed on a sample considered reasonably representative of the
dominant soil type encountered during the subsurface exploration. A laboratory maximum dry
density of 125 pcf at optimum moisture content of 8.5% was determined in general accordance
with test method ASTM D 1557.
Chemical Analysis
Chemical analyses as indicated below were performed by our subcontractor. Tests results are
enclosed.
Sulfate Content
Analysis to determine the water-soluble sulfate content was performed by others in general
accordance with California Test No. 417. Results of the testing indicated a 0.018% by weight
sulfate content, which is considered "not applicable" (negligible) as per Table 4.2.1 of ACI 318.
Resistivity and pH
A representative soil sample was tested by others for resistivity and pH in general accordance
with California Test 643. The results of the testing are included herein indicate a resistivity of
3400 ohms-cm and a pH of 7.35.
Chloride
Analysis to determine the chloride content was performed by others in general accordance
with California Test No. 422. Results of the testing indicated I 02ppm.
5. GEOLOGIC AND SOILS CONDITIONS
5.1 REGIONAL SETTING
The project is situated in the Peninsular Ranges Geomorphic Province. This province
encompasses an area that extends approximately 900 miles from the Transverse Ranges south
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SO3
April 15, 2016
Page 5
to the tip of Baja California, and varies in width from roughly 30 to I 00 miles. The province is
characterized by mountainous terrain in the east comprised dominantly of Mesozoic igneous
and metamorphic rocks, with relatively low-lying coastal terraces to the west underlain by late
Cretaceous, Tertiary, and Quaternary age sedimentary bedrock.
The Peninsular Ranges are traversed by several major active faults. The Newport-Inglewood
Rose Canyon, Whittier-Elsinore, San Jacinto, and San Andreas faults are major active fault
systems located north-northeast of the site and the Rose Canyon, Coronado Bank, and San
Diego Trough are active faults located to the west. Major tectonic activity associated with
these and other faults within this regional tectonic framework is marked by right-lateral and
strike-slip movement.
The province is characterized by major mountain ranges with intervening alluviated, broadly
synclinal valleys and narrow stream canyons. The province subdivides into several individual
ranges and geologic features. The major subdivisions of interest are the Santa Ynez Mountains,
Central Ventura County Mountains, Santa Monica Mountains, Ventura/Soledad Basin, Ridge
Basin, San Gabriel Mountains, Los Angeles Basin, San Bernardino Mountains, and the Eastern
Boundary Ranges.
While the underlying geology of northern San Diego County is rather complex, in the more
immediate area of coastal north county much of the near shore terraced geomorphology is
underlain Paralic Deposits. Regional geologic mapping by Kennedy and Tan, 2005 (see Figure 3
-Regional Geologic Map) indicates this immediate area is underlain by a deposit designated as
Qop 6-7 which are relatively recent deposits.
5.2 GENERAL SOIL CONDITIONS
A brief description of the earth materials encountered is presented in the following sections.
The subsurface profile at this site consists of Quaternary old paralic deposits (see Figure 3 -
Regional Geologic Map).
Quaternary-aged old paralic deposits (formerly referred to as terrace deposits) underlie the
site at depth and generally consist of massively bedded, weakly to slightly cemented, medium
dense, sands. Approximately the upper two (2) feet is silty to clayey and loose due to
weathering. Overlying the paralic deposits in some areas are older fill soils these materials
likely date to original site development. The fills are considered not to be suitable for
structural support.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
5.3 SURFACE AND GROUNDWATER
5.3.1 Surface Water
Project No. 3447-5D3
April 15, 201 6
Page 6
If encountered during the earthwork construction, surface water on this site is the result of
precipitation or surface run-off from surrounding site primarily to the northeast. Area
drainage is generally directed to the west. Provisions for surface drainage have been
incorporated into the grading plans by the project civil engineer.
5.3.2 Groundwater
Groundwater was not encountered in our exploratory excavations. The site is approximately
50 feet above sea level and given the proximity to the ocean the groundwater level is probably
at least 30 feet below the surface. No natural groundwater condition is known to be present
which would impact site development. However, groundwater or localized seepage can occur
due to variations in rainfall, irrigation practices, and other factors not evident at the time of
this evaluation.
5.4 FAUL TING 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 not
situated within an "Alquist-Priolo" Earthquake Fault Zone, or a State of California Special Studies
Zone, or any City designated zone.
5.4.1 Seismic Design Parameters
The site is located at approximately 33.1633 Latitude and -117.3506 Longitude. Site spectral
accelerations (Ss and SI), for 0.2 and 1.0 second periods for a risk targeted one (I) percent
probability of exceedance in 50 years (MCER) were determined from the USGS
Earthquake Hazards Program, U.S. Seismic Design Maps Website
(http://earthquake.usgs.gov/designmaps/us/application.php ). The site is considered a Site Class
"C", due the shallow paralic deposit. The results are presented in the following table:
G EOTEK
Vest.a Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Table 4.4 -SITE SEISMIC PARAMETERS
Mapped 0.2 sec Period Spectral Acceleration, Ss (.g)
Mapped 1.0 sec Period Spectral Acceleration, SI (2)
Maximum Considered Earthquake Spectral Response
Acceleration Parameter at 0.2 Second, SMS (2)
Maximum Considered Earthquake Spectral Response
Acceleration Parameter at I .0 second, SM I (2)
Design Spectral Response Acceleration Parameter for 0.2
Second, SOS (2)
Design Spectral Response Acceleration Parameter for 1.0
Second, SD I (2)
Site Coefficient, Fa
Site Coefficient, Fv
1.155
0.443
1.155
0.601
0.770
0.401
1.00
1.357
Project No. 3447-5D3
April 15, 2016
Page 7
Seismically resistant structural design in accordance with applicable code should be followed
during the design of the structure. The California Building Code (CBC) has been developed to
reduce the potential for structural damage. However, some level of damage as the result of
ground shaking generated by nearby earthquakes is considered likely in this general area.
5.5 LIQUEFACTION AND SEISMICALLY INDUCED SETTLEMENT
Liquefaction describes a phenomenon in which cyclic stresses, produced by earthquake-
induced ground motion, create excess pore pressures in relatively cohesion less soils. These
soils may thereby acquire a high degree of mobility, which can lead to lateral movement,
sliding, consolidation and settlement of loose sediments, sand boils and other damaging
deformations. This phenomenon occurs only below the water table, but, after liquefaction has
developed, it can propagate upward into overlying non-saturated soil as excess pore water
dissipates.
The factors known to influence liquefaction potential include soil type and grain size, relative
density, groundwater level, confining pressures, and both intensity and duration of ground
shaking. In general, materials that are susceptible to liquefaction are loose, saturated granular
soils having low fines content under low confining pressures.
The City of Carlsbad General Plan does not indicate the site is in a liquefaction study area.
The liquefaction potential on the site is considered negligible due to the relatively dense nature
of the underlying materials at the depths explored and expected depths to groundwater.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 271 S Roosevelt Street, Carlsbad, California
5.6 OTHER SEISMIC HAZARDS
Project No. 3447-SD3
April 15, 2016
Page 8
Evidence of ancient landslides or slope instabilities at this site was not observed during our
investigation. Thus, the potential for landslides is considered negligible.
The potential for secondary seismic hazards such as seiche and tsunami are considered to be
negligible due to site elevation and distance from an open body of water.
6. CONCLUSIONS AND RECOMMENDATIONS
6.1 GENERAL
The proposed site development appears feasible from a geotechnical viewpoint provided that
the following recommendations are incorporated into the design and construction phases of
development.
Geotechnical conditions do not appear to represent significant constraints on site
development. Although relatively thick loose soil is present requiring removal and
recompaction. Import soil is planned so that the final foundation recommendations will largely
depend on the soils brought on site. Retaining walls are planned on the site perimeters, these
walls should be founded at sufficient depth to avoid imparting loads on any offsite structures.
6.2 EARTHWORK CONSIDERATIONS
Earthwork and grading should be performed in accordance with the applicable grading
ordinances of City of Carlsbad, the 2013 California Building Code (CBC), and
recommendations contained in this report. Appendix A -Grading Guidelines outline general
procedures and do not anticipate all site specific situations. In the event of conflict, the
recommendations presented in the text of this report should supersede those contained in
Appendix A
6.2.1 Site Clearing
The existing structures including foundations should demolished and removed from the site.
Existing landscaping and other surface improvements should be removed and properly
disposed of off-site. The site will need to be cleared including any debris present. Care should
be taken during site grading to check for any buried foundations or utilities, vegetation, roots,
trash and debris, and properly dispose of these materials offsite. Our experience is that
GEO TE K
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-S03
April 15, 2016
Page 9
abandoned septic system are present on some sites in the older sections of Carlsbad and could
be encountered during site grading. If so it would require appropriate removal and backfilling.
Areas of loose soil, root systems or other undesirable items may be encountered. Any holes
resulting from site clearing, tree removal, etc. should be observed by the project geotechnical
consultant prior to filling. The voids should be filled with properly compacted fill materials
with expansion characteristics similar to the existing onsite soils.
6.2.2 Fills
The onsite soils are considered suitable for reuse as engineered fill provided they are free from
vegetation, debris and other deleterious material. Undercut areas should be brought to final
subgrade elevations with fill materials placed and compacted. Soil should be moisture
conditioned to at least optimum moisture content and compacted to a minimum of 90%
relative compaction per ASTM Test Designation I 557 in accordance with the general grading
guidelines presented in Appendix A
6.2.3 Removals
The need for removals will depend largely on the limits of existing fills and the finish site
grades. In the rear (west portion) of the site removals up to about 6 feet are expected. In
areas outside the fill removals are expected to be on the order of 3 feet. Locally deeper
removals may be encountered.
Removals should be sufficient to provide a minimum of 2 feet of engineered fill beneath the
foundation. Removal should also be sufficient to assess that all footing, utilities, etc. associated
with any prior development are removed.
Removals should extend as close to the property lines as prudent. Structural set-backs may be
warranted around the perimeter on the site.
The bottom of all removals should be scarified to an approximate depth of eight (8) inches,
brought to at or above optimum moisture content, and then recompacted to minimum project
standards prior to fill placement.
Care should be taken during removals to protect adjoining improvements. It may be necessary
to excavate small sections adjacent to the retaining walls on the adjoining properties.
6.2.4 Excavation Characteristics
Excavation in the onsite materials is expected to be easy to moderate using moderate to
heavy-duty grading equipment in good operating conditions.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SO3
April 15, 2016
Page 10
All temporary excavations for grading purposes and installation of underground utilities should
be constructed in accordance with local and Cal-OSHA guidelines. Temporary excavations
within the onsite materials are anticipated to be stable at I: I inclinations for cuts less than
seven (7) feet in height.
6.2.5 Shrinkage, Bulking, and Subsidence
Several factors will impact earthwork balancing on the site, including shrinkage, bulking,
subsidence, trench spoil from utilities and footing excavations, as well as the accuracy of
topography.
Shrinkage, bulking and subsidence are primarily dependent upon the degree of compactive
effort achieved during construction. While these factors can be highly variable for planning
purposes we suggest the following be applied:
• Materials that are removed and recompacted should be anticipated to shrink
approximately IO to 20 percent.
• Compaction of removal bottoms resulting in a loose of about 0.0 I feet
• Consideration for volume of lose due to site clearing and demolition. This may be a
significant factor depending on specific conditions. For initial estimating purpose an
average lose of about 6 to 12 inches should be expected.
6.2.6 Import Soil
Import soil preferably should have an Expansion Index (El) of 40 or less. It is recommended
that import source(s) be sampled and tested by GeoTek at least 72 hours prior to import onto
the site. Test results can then be discussed with client, who can determine whether the
materials are acceptable to them. Import materials are likely to control foundation and
pavement design and also the soils chemistry at the completion of grading.
It is recommended that if possible import be obtained from a single source and be fairly
uniform in nature. If feasible the site should be brought to a relatively uniform depth from
finished grade and then import materials brought in. It would be advisable to leave drive areas
low to accommodate footing and trench spoil rather than finding the need to export at the end
of the project.
6.3 DESIGN RECOMMENDATIONS
6.3.1 Foundation Design Criteria
Preliminary foundation design criteria for a conventional foundation system, in general
conformance with the 2013 CBC, are presented herein. These are typical design criteria and
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SO3
April 15, 2016
Page 11
are not intended to supersede the design by the structural engineer. We have assumed that
foundations will support a minimum of two floors.
Soils encountered on site are in borings are considered to be expansive per the CBC.
However, the import soils are likely to control the final foundation design. Below are
preliminary foundation recommendations assuming soils with El ~ 40, Pl < I 0. This material is
not considered to be expansive within the guidelines of the CBC. If more expansive soil is
placed beneath the foundations then modified recommendations would be required. Post-
tension foundation may be warranted in some instances. Additional laboratory testing should
be performed at the completion of site grading to verify the potential of the subgrade soils.
A summary of our preliminary foundation design recommendations are presented in Table
6.3.1 below:
TABLE 6.3.1 -MINIMUM DESIGN REQUIREMENTS
DESIGN PARAMETER 0<El~40 & Pl< I 0
Foundation Depth or Minimum Supporting Two Floors -18
Perimeter Beam Depth (inches below
lowest adjacent _grade)
Supporting Three Floors -24
Foundation Width (Inches)
Supporting Two Floors -15
Supportin_g Three Floors -18
Minimum Slab Thickness (inches) 4 (actual)
Minimum Slab Reinforcing
No. 3 rebar 24" on-center,
placed in middle third of slab
Minimum Footing Reinforcement
Four (4) No. 4 Reinforcing Bars
Two (2) top and Two (2) bottom
Presaturation of Subgrade Soil
(Percent of Optimum/Depth in Inches) 120%/ I 2 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:
6.3. I. I An allowable bearing capacity of 2000 pounds per square foot (psf) may be used for design
of continuous and perimeter footings 18 inches deep and 15 inches wide, and pad footings
24 inches square and 24 inches deep. This value may be increased by 200 pounds per
square foot for each additional 12 inches in depth and I 00 pounds per square foot for each
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SD3
April 15, 2016
Page 12
additional 12 inches in width to a maximum value of 3,000 psf Additionally, an increase of
one-third may be applied when considering short-term live loads (e.g. seismic and wind loads).
6.3. I .2 The passive earth pressure may be computed as an equivalent fluid having a density of 150
psf per foot of depth, to a maximum earth pressure of 2,000 psf for footings founded on
compacted fill. A coefficient of friction between soil and concrete of 0.25 may be used with
dead load forces. The upper one foot of soil below the adjacent grade should not be used in
calculating passive pressure. When combining passive pressure and frictional resistance, the
passive pressure component should be reduced by one-third.
6.3. I .3 A grade beam, 12 inches wide by 18 inches deep (minimum), should be utilized across large
opening or garage entrances. The base of the grade beam should be at the same elevation
as the bottom of the adjoining footings.
6.3. I .4 Isolated exterior footings should be tied back to the main foundation system in at least one
direction.
6.3. I .5 Footing excavations should be free of loose/sloughed materials and be neatly trimmed at the
time of concrete placement
6.3. I .6 It should be noted that considering footing and other excavations may have a tendency to
slough particularly as the soil dries.
6.3. I. 7 All loose material should be removed from footing prior to pouring concrete. It is likely that
this will result in additional concrete being needed.
6.3. I .8 If sides of footings are blocked out or formed to limit concrete over-pour then any adjoining
void should be properly backfilled a~er concrete is allowed to cure.
6.3.l Underslab Compaction Recommendations
6.3.2. I 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.
6.3.2.2 Soils from the footing excavations should not be placed in the slab-on-grade areas unless
properly compacted and tested.
6.3.2.3 Under-slab utility trenches should be compacted to project specifications. Compaction should
be achieved with a mechanical compaction device. If backfill soils have dried out, they should
be thoroughly moisture conditioned prior to placement in trenches.
6.3.2.4 Utility trench excavations should be shored or laid back in accordance with applicable
CAL/OSHA standards.
6.3.2.5 On-site materials may not be suitable for use as bedding material, but will be suitable as
backfill. Jetting of native soils will not be acceptable.
6.3.3 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. As a minimum, the capillary break and moisture
retarder should be in conformance with the 2013 CBC Section 1910.1 or, if adopted by the
local agency, the 20 IO California Green Building Standards Code (CALGreen) Section 4.505.2.
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 puncture
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-$D3
April I 5, 20 16
Page 13
resistant than thinner ones. Products specifically designed for use as moisture/vapor retarders
may also be more puncture resistant. It is Geo T ek's opinion that a minimum IO mil thick
membrane with joints properly overlapped and sealed should be used.
Moisture and vapor retarding systems constructed in compliance with Code minimums 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. 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.
6.3.4 Settlement
The anticipated total and differential settlements are estimated less than I inch and I /2 inch
over 40 feet of horizontal distance, respectively.
6.3.5 Foundation Set Backs
6.3.5. I General Set Backs
Minimum setbacks to all foundations should comply with the 2013 CBC. Any
improvements not conforming to these setbacks may be subject to lateral movements
and/or differential settlements:
♦ The outside bottom edge of all footings should be set back a minimum of H/3 (where H
is the slope height) from the face of any descending slope. The setback should be at
least 7 feet and need not exceed 40 feet.
♦ The bottom of all footings for structures near retaining walls should be deepened so as
to extend below a I : I projection upward from the bottom inside edge of the wall stem.
♦ The bottom of any existing foundations for structures should be deepened so as to
extend below a I: I projection upward from the bottom of the nearest excavation.
♦ Structures should be setback a minimum of H/3 to a maximum of 15 feet from any
ascending slope, unless specifically reviewed and otherwise found acceptable.
6.3.5.2 Bioretention Setbacks
♦ Foundations should also be set back from the bio-retention basin. These set backs may
vary as follows:
♦ Provided the gravel section in the basin is compacted using a vibratory compactor with
12 inch thick lifts then footings within six feet of the basins should be a minimum of 30
inches deep or extend below a plane project upward at I: I from the top of the nearest
gravel in a bioretention basin.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
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♦ If the gravel section is not compacted then the footing should extend below a plan
project upward at I: I from the bottom of the nearest gravel in a bioretention basin.
6.3.6 Soil Corrosivity
The soil resistivity at this site was tested in the laboratory on representative samples collected
during the field investigation. The results of the testing indicate that the onsite soils are
considered "moderately corrosive" to buried metal in accordance with current standards
commonly used by corrosion engineers. These characteristics are considered typical of soils
commonly found in southern California. We recommend that a corrosion engineer be
consulted to provide recommendations for proper protection of buried metal at this site. It is
important to note that import soils may well control soil corrosivity.
6.3.7 Soil Sulfate Content
The sulfate content was determined in the laboratory for a representative onsite soil sample.
The results indicate that the water soluble sulfate range is 0.018 percent by weight, which is
considered "not applicable" (i.e. negligible) as per Table 4.2.1 of ACI 318. Concrete mix design
may be selected accordingly.
6.4 RETAINING WALL DESIGN AND CONSTRUCTION
6.4.1 General Design Criteria
Recommendations presented herein may apply to typical masonry or concrete vertical
retaining walls to a maximum height of up to 6 feet. Perimeter walls should be founded to
avoid placing any additional load on off site structures. Additional review and recommendations
should be requested for higher walls.
Retaining wall foundations, embedded a minimum of 18 inches into engineered fill or dense
paralic deposits, should be designed using an allowable bearing capacity of 2,000 psf. An
increase of one-third may be applied when considering short-term live loads (e.g. seismic and
wind loads). Bearing capacity may be increased by 200 psf for each additional foot of width or
depth to a maximum of 3,000 psf. The passive earth pressure may be computed as an
equivalent fluid having a density of 200 psf per foot of depth, to a maximum earth pressure of
2,500 psf. A coefficient of friction between soil and concrete of 0. 3 may be used with dead
load forces. The upper one foot of soil below the adjacent grade should not be used in
calculating passive pressure. When combining passive pressure and frictional resistance, the
passive pressure component should be reduced by one-third.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
6.4.2 Cantilevered Walls
Project No. 3447-$D3
April 15, 2016
Page 15
The recommendations presented below are for cantilevered retaining walls up to 6 feet high.
Active earth pressure may be used for retaining wall design, provided the top of the wall is not
restrained from minor deflections. An equivalent fluid pressure approach may be used to
compute the horizontal pressure against the wall. Appropriate fluid unit weights are given
below for specific slope gradients of the retained material. These do not include other
superimposed loading conditions such as traffic, structures, seismic events, or adverse geologic
conditions.
TABLE 6.4.2 -ACTIVE EARTH PRESSURES
Surface Slope of Retained Equivalent Fluid Pressure Equivalent Fluid Pressure
Materials (PCF) (PCF)
(H:V) Select Backfill* Native Backfill
Level 35 45
2:1 50 60
* Select backfill may consist of Class 2 permeable filter materials, Class 2 aggregate base
or Sand with an SE> 30. Backfill zone includes area between back of wall to plane (I: I, h:v) up
from back of wall foundation to ground surface. Some native soil may be considered as select
backfill.
6.4.3 Wall Backfill and Drainage
Wall backfill should include a minimum one foot wide section of % to I-inch clean crushed
rock (or approved equivalent). The rock should be placed immediately adjacent to the back of
wall and extend up from the backdrain to within approximately 12 inches of finish grade. The
upper 12 inches should consist of compacted onsite materials. Presence of other materials
might necessitate revision to the parameters provided and modification of wall designs. The
backfill materials should be placed in lifts no greater than 8-inches in thickness and compacted
at 90% relative compaction in accordance with ASTM Test Method D 1557. Proper surface
drainage needs to be provided and maintained.
Retaining walls should be provided with an adequate pipe and gravel backdrain system to
prevent build up of hydrostatic pressures. Backdrains should consist of a 4-inch diameter
perforated collector pipe (Schedule 40 PVC, SDR 35, or approved equivalent) embedded in a
minimum of one cubic foot per lineal foot of % to one inch clean crushed rock or equivalent,
wrapped in filter fabric. Panel drains may be used as an alternative. The drain system should
be connected to a suitable outlet. A minimum of two outlets should be provided for each
drain section. Spacing between drain outlets should not exceed I 00 feet.
Walls from 2 to 4 feet in height may be drained using localized gravel packs behind weep holes
at IO feet maximum spacing (e.g. approximately 1.5 cubic feet of gravel in a woven plastic bag).
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-5D3
April 15, 2016
Page 16
Weep holes should be provided or the head 101nts omitted in the first course of block
extended above the ground surface. However, nuisance water may still collect in front of the
wall.
6.4.4 Restrained Retaining Walls
Any retaining walls that will be restrained prior to placing and compacting backfill material or
that have reentrant or male corners, should be designed for an at-rest equivalent fluid pressure
of 65 pcf, plus any applicable surcharge loading. For areas of male or reentrant corners, the
restrained wall design should extend a minimum distance of twice the height of the wall
laterally from the corner.
6.5 BIORETENTION
Bioretention treatment/detention basins are planned along the northeast side of the site
paralleling Roosevelt Street and also on the northwest side immediately behind the planned
retaining wall. These will act as treatment, retention and infiltration basins.
For the basins paralleling Roosevelt, the plan indicates that there will be approximately a 1.0 to
1.5 feet high slope starting at the foundations and extending to the basin floor. The filtration
sections will then extend vertically to a depth of at least three feet. The filtration section
includes a layer of 3/,.inch gravel overlain by two inches of 3/8" gravel in turn overlain by two
(2) feet of "bioretention engineered soil" (BES) . By design, the BES contains a high percentage
organic material and is not typically compacted, as such it is not considered structural fill.
Foundation design recommendations have been modified to address this. Consideration should
be given to compacting the gravel to limit the potential for future settlements. Compaction
would decrease foundation setbacks as discussed in Section 6.3.5.2 above.
The 3/,." gravel is fairly coarse with open voids that may be subject to migration of finer grained
soil (sand) to fill the voids. The gravel should be wrapped with filter fabric (Tencate Mirafi
140N or similar). With the filter fabric the fine (3/8") gravel is not needed from a geotechnical
perspective. The walls on the basins toward the structures should be lined with an
impermeable membrane to limit near surface infiltration.
6.6 PAVEMENT DESIGN
The site is to have a proportionately high volume of import soils. Additionally there are several
soil types on the project as the fill in the western portion of the site that was apparently
import material. As such, probable subgrade soils cannot be reasonably anticipated and tested
at this time. Design of pavements should be based on R-value testing of subgrade soil. Based on
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SD3
April 15, 2016
Page 17
our experience in the area and provided that low expansion, well graded soil is generally
imported to the site then it is reasonable to assume for preliminary purposes R-values of 20 or
higher for subgrade soils. The only indicated hard pavement surfaces on Grading Plan are
limited areas of concrete pavement in the driveways for the project. Subject to verification of
subgrade R-value when possible it is recommended that the concrete sections be a minimum of
five (5) inches thick and reinforced with number 3 reinforcing bar at 24 inches on center. This
exceeds the City minimum of 4 inches thick for driveways and parking lots.
6. 7 FLA TWORK
Assuming that low expansive soils are placed at finish grade then concrete flatwork may be 4
inches thick. If desired to achieve better cracking control 6"x6" No.6 WWM may be used as
reinforcement and placed mid height in the concrete.
6.8 POST CONSTRUCTION CONSIDERATIONS
6.8.1 Landscape Maintenance and Planting
Water has been shown to weaken the inherent strength of soil, and slope stability is
significantly reduced by overly wet conditions. 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. An abatement program to control ground-burrowing rodents
should be implemented and maintained. This is critical as burrowing rodents can decrease the
long-term performance of slopes.
It is common for planting to be placed adjacent to structures in planter or lawn areas. This will
result in the introduction of water into the ground adjacent to the foundation. This type of
landscaping should be avoided. If used, then extreme care should be exercised with regard to
the irrigation and drainage in these areas. Waterproofing of the foundation and/or subdrains
may be warranted and advisable. We could discuss these issues, if desired, when plans are
made available.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
6.8.2 Drainage
Project No. 3447-S03
April IS, 2016
Page 18
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. Pad drainage should be directed toward
approved area(s) and not be blocked by other improvements.
It is the owner's responsibility to maintain and clean drainage devices on or contiguous to their
lot. In order to be effective, maintenance should be conducted on a regular and routine
schedule and necessary corrections made prior to each rainy season.
6.9 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS
We recommend that site grading, specifications, and foundation plans be reviewed by this
office prior to construction to check for conformance with the recommendations of this
report. We also recommend that GeoTek representatives be present during site grading and
foundation construction to check for proper implementation of the geotechnical
recommendations. The owner/developer should have GeoTek's representatives perform at
least the following duties:
♦ Observe site clearing and grubbing operations for proper removal of all 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, a construction observation and compaction report can be provided by Geo T ek,
which can comply with the requirements of the governmental agencies having jurisdiction over
the project. We recommend that these agencies be notified prior to commencement of
construction so that necessary grading permits can be obtained.
7. INTENT
It is the intent of this report to aid in the design and construction of the proposed
development. Implementation of the advice presented in Section 6 of this report is intended
to reduce risk associated with construction projects. The professional opinions and
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
Project No. 3447-SDJ
April 15, 2016
Page 19
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 the area explored within the boundaries of the
subject residential lot and as shown on the enclosed Site Explorations Map (Figure 2). This
evaluation does not and should in no way be construed to encompass any areas beyond the
specific area of the proposed construction 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, our proposal (P3-0300 I I 2SD dated March
29, 2012) and geotechnical engineering standards normally used on similar projects in this
region.
8. 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 conclusion 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.
GEOTEK
Vesta Pacific Development
Updated Preliminary Geotechnical Evaluation
2685, 2687 & 2715 Roosevelt Street, Carlsbad, California
9. SELECTED REFERENCES
Project No. 3447-SO3
April 15, 2016
Page 20
ASTM, 2011, "Soil and Rock: American Society for Testing and Materials," volumes 4.08 and
4.09.
California Code of Regulations, Title 24, 2013 "California Building Code,"
California Department of Water Resources groundwater well data (http://wdl.water.ca.gov).
Geo T ek, Inc., In-house proprietary information.
USGS, Earthquake Hazards Program, U.S. Seismic Design Maps Website
(http://earthquake.usgs.gov/ designmaps/us/appl i cati on.php).
City Carlsbad General Plan, obtained on City Carlsbad Web Site
(http://www.carlsbadca.gov/services/departments/planning/pages/general-plan.aspx)
GEOTEK
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1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 20 14
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Site Location Map
Roosevelt
Carlsbad, California
Figure 1
_____ ..,..... ___ ,,~---.ao --------------------------'----------'-------.-... -----
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Approximate Scale
1 inch = 35 feet
Locations are approximate
PN: 3447-$D3
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 2014
ROOSE YE~ T STREET •
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Base Map Adopted from:
"Conceptual Grades and
Drainage Plan" prepared by
Pasco Laret Suiter &
Associates
Site Exploration Plan
2685 & 2687 Roosevelt Street
Carlsbad, California
Figure 2
Logs of Exploratory Excavations
Roosevelt Street
Boring B-1
0 -0.5' Reddish brown, hard, slightly moist, gravelly clayey Silt,
2 -5 ' Fill : variable soils types import and probably native soil, from Red brown, slightly moist,
fine to medium grained, Sand; Grey green, silty clay; brown, silty Sand
5 -6.5' Buried natural soil? Light red brown, medium stiff, slightly moist to moist, Silty clay to
clayey Silt, porous
6.5 to 7.5 Paralic deposits: Medium dense but friable, slightly moist, silty Sand to clean Sand.
Total depth 7.5'
Boring B-2'
0 -I' Fill?: Reddish brown, hard, slightly moist, gravelly clayey Silt, porous. Refused on gravel at
12 inches
Boring moved approximately one foot
Boring B-2A
0 -1.5' Fill?: Reddish brown, hard, slightly moist, gravelly clayey Silt, porous. Refused on gravel
at 18 inches gravel may be from upper portion on hole.
Boring B-3
0 -I' Native soil?: Reddish brown, hard, slightly moist, silty Clay, gravel at 12 inches practical
Boring moved approximately two foot
Boring B-JA
0 -I' Native soil: Reddish brown, hard, slightly moist, silty Clay,
I to 1.5 feet transitions to clay silt then silty Sand
1.5 to 2.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand.
Boring moved approximately two foot
Boring B-4
0 -0.5' Grass layer and abundant roots in clayey Silt
0.5 -I Native soil: Reddish brown, hard, slightly moist, clayey Silt
I to 1.5 feet transitions to clay silt then silty Sand
1.5 to 3.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand.
Boring B-5 (planter area southern PL)
0 -0.5' Abundant organic matter in clayey Silt
0.5 -I Native soil: Reddish brown, hard, slightly moist, clayey Silt
I to 2.0 feet transitions to clay silt then silty Sand
2.0 to 3.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand
becomes less silty with depth.
Boring B-6 (planter area southern PL)
0 -0.5' Abundant organic matter in clayey Silt to silty Clay
0.5 -1.5 Native soil: Reddish brown, hard, slightly moist, Silty Clay
1.5 to 2.5 feet transitions to clay silt then silty Sand
2.5 to 3.0 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand
becomes less silty with depth.
Project No: 3447-SD3
Not to scale
n
GEOTEK
PN: 3447-SDJ
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 20/4
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.
Regional Geologic Map
Roosevelt Project
Carlsbad, California
Figure 3
APPENDIX A
Grading Guidelines
2685, 2687 & 2715 Roosevelt Street
Carlsbad, California
Project No. 3447-$D3
GEOTEK
EARTHWORK GRADING GUIDELINES
EARTHWORK GRADING GUIDELINES
APPENDIX A
Page I
Site grading should be performed to at least the minimum requirements of the governing
agencies, the 2013 California Building Code and the guidelines presented below.
Site Clearing
Trees, dense vegetation, and other deleterious materials should be removed from the site.
Non organic debris o r concrete may be placed in deeper fill areas per the recommendations
of the Soils Engineer.
Prudent efforts should be made by the contractor to remove all organic or other
deleterious material from the fill. This is especially important when grading is occurring near
the natural grade. All operators should be aware of these efforts. Even the most diligent
efforts may result in the incorporation of some materials. Laborers may be required as
"root pickers".
Subdrainage
Subdrains are not anticipated in conjunction with the proposed grading. Should conditions
be encountered necessitating subdrain placement, specific recommendations will be offered.
Treatment of Existing Ground
Vegetation, rubbish and other deleterious materials should be disposed of off site.
Loose and compressible materials (including weathered rock, deposits of alluvium and
colluvium, poorly compacted or weathered fill, etc.) should be removed unless otherwise
indicated in the text of this report. Deeper removals than indicated in the text of the
report may be necessary due to saturation during winter months, as the result of changes
over time or due to variations in the subsurface.
Subsequent to removals, the ground surface should be processed to a depth of eight (8)
inches, moistened to near optimum moisture conditions and compacted to fill standards.
Exploratory test excavations (backhoe or dozer trenches) still remaining after completion of
basic removals should be excavated and filled with compacted fill if they can be located.
Fill Placement
It should be realized that proper fill compaction is largely procedural and is the responsibility
of the grading contractor. Testing and observation by the Soil Engineer, while helpful to
EARTHWORK GRADING GUIDELINES APPENDIX A
Page 2
evaluate the efforts of the contractor, should not be considered as a substitute for proper
and consistent procedures. Compaction testing is specific to the test location; variable test
results could be obtained in other locations. Technicians typically do not see all that occurs
during construction. Deviation from the procedures found to produce adequate test results
might result in inadequate compactive efforts. The need for properly maintained equipment
and trained personnel operating it, cannot be over emphasized.
On site soil and bedrock may typically be used for compacted fill; however, some special
processing, placement or handling may be required (see report).
Material used in the compacting process should be evenly spread, moisture conditioned,
processed, and compacted in thin lifts not to exceed six (6) inches in thickness to obtain a
uniformly dense layer. The fill should be placed and compacted in nearly horizontal layers,
unless otherwise found acceptable by the Soils Engineer.
If the moisture content or relative density varies from that acceptable to the Soils Engineer,
the Contractor should rework the fill until it is in accordance with the following:
Moisture content of the fill should typically be at or above optimum moisture. Moisture
should be evenly distributed without wet and dry pockets. Pre-watering of cut or removal
areas should be considered in addition to watering during fill placement, particularly in clay
or dry surficial soils.
Each six (6) inch layer should be compacted to at least 90 percent of the maximum density
in compliance with the testing method specified by the controlling governmental agency. In
this case, the testing method is ASTM Test Designation D-1557.
Side-hill fills should have an equipment-width key at their toe excavated through all surficial
soil and into competent material and tilted back into the hill. As the fill is elevated, it should
be benched through surficial soil and slopewash and into competent bedrock or other
material deemed suitable by the Soils Engineer.
Rock fragments less than eight (8) inches in diameter may be utilized in the fill, provided:
I. They are not placed in concentrated pockets;
2. There is a sufficient percentage of fine-grained material to surround the rocks;
3. The distribution of the rocks is observed by and acceptable to the Soils Engineer.
Rocks greater than eight (8) inches in diameter should be taken off site, or placed in
accordance with the recommendations of the Soils Engineer in areas designated as suitable
for rock disposal.
EARTHWORK GRADING GUIDELINES APPENDIX A
Page 3
In clay soil large chunks or blocks are common; if in excess of eight (8) inches minimum
dimension then they are considered as oversized. Sheepsfoot compactors or other suitable
methods should be used to break the up blocks.
The Contractor should be required to obtain a minimum relative compaction of 90 percent
out to the finished slope face of fill slopes. This may be achieved by either overbuilding the
slope and cutting back to the compacted core, or by direct compaction of the slope face
with suitable equipment. Given the low height of slopes on this project overbuilding the
slope and cutting back to the compacted core is recommended. Other methods should be
discussed with and accepted by this firm prior to implementing.
Fill over cut slopes should be constructed in the following manner:
All surficial soils and weathered rock materials should be removed at the cut-fill interface.
This will generally result in the cut-fill catch point or daylight line being at least several feet
lower than the elevation indicated on the plans.
A key at least one (I) equipment width wide and wide enough to accommodate the method
of compaction used should be excavated into competent materials and observed by the soils
engineer or his representative. The key should be tilted into slope with the heel being at
least I foot lower in elevation than the toe.
The cut portion of the slope should be roughed out leaving the slope about three (3) feet
"fat", to evaluate if stabilization of the cut section is necessary. If the contractor decides to
place the fill prior to cut excavation, then he should be responsible for any additional
earthwork created by the fill placement and due to the need to stabilize the cut portion of
the slope.
Transition lots (cut and fill) and lots above stabilization fills should be capped with a
minimum three (3) foot thick compacted fill blanket. Deeper overexcavation may be
recommended in some cases.
Cut pads shou ld be observed by the Engineering Geologist to evaluate the need for
overexcavation and replacement with fill. This may be necessary to reduce water infiltration
into highly fractured bedrock or other permeable zones, and/or due to differing expansive
potential of materials beneath a structure. The overexcavation should be at least three (3)
feet. Deeper overexcavation may be recommended in some cases.
In cut areas exploratory test excavations (backhoe or dozer trenches) remaining after
completion of cut excavation and removal of all surficial soils and weathered rock materials
should be excavated and filled with compacted fill if they can be located. Treatment of
borings can be determined during construction.
EARTHWORK GRADING GUIDELINES
Grading Observation and Testing
APPENDIX A
Page 4
Observation of the fill placement should be provided by the Soils Engineer during the
progress of grading.
In general, density tests would be made at intervals not exceeding two (2) feet of fill height
or every 1,000 cubic yards of fill placed. These criteria will vary depending on soil
conditions and the size of the fill.
In any event, an adequate number of field density tests should be made to evaluate if the
compactive efforts used by the contractor are such that the required compaction and
moisture content is generally being obtained.
As proper fill compaction is largely procedural, adequate test results should not be
considered as a substitute for proper procedures. This testing is, by its nature, specific to
the test location. Variable test results could be obtained in other locations.
Density tests may be made on the surface material to receive fill, as required by the Soils
Engineer.
Cleanouts, processed ground to receive fill, key excavations, subdrains and rock disposal
areas / procedures should be observed by the Soils Engineer prior to placing any fill. It will
be the Contractor's responsibility to notify the Soils Engineer when such areas are ready for
observation.
An Engineering Geologist should observe subdrain construction.
An Engineering Geologist should observe benching prior to and during placement of fill.
JOB SAFETY
General:
Job safety is of primary concern. The following outlines safety considerations for use by all
employees on multi-employer construction sites. On ground personnel are at highest risk of
injury and possible fatality on grading construction projects. The company recognizes that
construction activities will vary on each site and that job site safety is the contractor's
responsibility. However, it is imperative that all personnel be safety conscious to avoid
accidents and potential injury.
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of our field personnel on grading
and construction projects.
EARTHWORK GRADING GUIDELINES APPENDIX A
Page 5
Safety Meetings: Our field personnel are directed to attend the contractor's regularly
scheduled safety meetings.
Safety Vests: Safety vests are provided for and are to be worn by our personnel where
necessary.
Safety Flags: Two safety flags are provided to our field technician; one is to be affixed to the
vehicle when on site, the other is to be placed atop the spoil pile on all test pits.
In the event that our personnel do not follow the above, we request that the contractor
contact our office.
Test Pits Location, Orientation and Clearance:
The technician is responsible for selecting test pit locations. The primary concern is the
technician's safety. However, it is necessary to take sufficient tests at various locations to
obtain a representative sampling of the fill. As such, efforts will be made to coordinate
locations with the grading contractors' authorized representatives (e.g. dump man, operator,
supervisor, grade checker, etc.), and to select locations following or behind the established
traffic pattern, preferable outside of current traffic. The contractors authorized
representative should direct excavation of the pit and safety during the test period. Again,
safety is the paramount concern.
Test pits should be excavated so that the spoil pile is placed away from oncoming traffic.
The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This
necessitates that the fill be maintained in a driveable condition. Alternatively, the contractor
may opt to park a piece of equipment in front of the test pits, particularly in small fill areas
or those with limited access.
When taking slope tests, the technician should park their vehicle directly above or below
the test location on the slope. The contractor's representative should effectively keep all
equipment at a safe operation distance (e.g. SO feet) away from the slope during testing.
The technician is directed to withdraw from the active portion of the fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in a
highly visible location.
In the event that the technician's safety is jeopardized or compromised as a result of the
contractor's failure to comply with any of the above, the technician is directed to inform
both the developer's and contractor's representatives in writing. If the condition is not
rectified, the technician is required, by company policy, to immediately withdraw and notify
their supervisor. The grading contractor representative will then be contacted in an effort
to effect a solution. No further testing will be performed until the situation is rectified. Any
EARTHWORK GRADING GUIDELINES APPENDIX A
Page 6
fill placed in the interim can be considered unacceptable and subject to reprocessing,
recompaction or removal.
In the event that the soil technician does not comply with the above or other established
safety guidelines, or if the contractor feels the technician, in any way, acts in an unsafe
manner, we request that the contractor bring this to the technicians attention and if not
rectified, notify the project manager or our office.
Effective communication and coordination between the contractors' representative and the
field technician(s) is strongly encouraged in order to implement the above safety program
and safety in general.
The safety procedures outlined above should be discussed at the contractor's safety
meetings. This will serve to inform and remind the equipment operators of these safety
procedures particularly the zone of non-encroachment.
Trench Safety:
It is the contractor's responsibility to provide safe access into trenches where compaction
testing is needed. Our personnel are directed not to enter any excavation which:
I . is 5 feet or deeper unless shored or laid back,
2. displays any evidence of instability, has any loose rock or other debris which could
fall into the trench, or
3. displays any other evidence of any unsafe conditions regardless of depth.
All utility trench excavations in excess of 5 feet deep, which a person enters, are to be
shored or laid back. Trench access should be provided in accordance with OSHA standards.
Our personnel are directed not to enter any trench by being lowered or "riding down" on
the equipment.
If the contractor fails to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify their supervisor. The
contractors' representative will then be contacted in an effort to effect a solution. All
backfill not tested due to safety concerns or other reasons could be subject to reprocessing
and/or removal.
APPENDIXB
City Review Comments
2685, 2687 & 2715 Roosevelt Street
Carlsbad, California
Project No. 3447-SD3
GEOTEK
( PRELIMINARY GEOTECHNICAL EVALUATION
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2685 & 268 Roosevelt Street
MADISON STREET PROJECT
CARLSBAD, CALIFORNIA
PREPARED FOR
VESTA PACIFIC DEVELOPMENT
181 8 2nd Street
SAN DIEGO, California
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PROJECT No. 3447-SDJ
VISTA, CALIFORNIA 92081
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JULY 21, 2014
GeoTek, Inc.
I ]EM Po.'\iCrt1,1 /lv<•nu<'. S,11a, A Vise;,, ( A 9208 I 850$
('60) :,99 0S09 (760) 599 0593 www.p,cocckusJ co1•1
Vesta Pacific Development
1818 Second Avenue
San Diego, California 920 I I
Attention:
Subject:
Mr. Geoff McComic
Preliminary Geotechnical Evaluation
2685 & 2687 oosevelt Street
Carlsbad, California ~ /_ 7/5)
Dear Mr. McComic:
July 21 , 2014
Project No. 3447-SD3
We are pleased to provide herewith the results of our preliminary geotechnical evaluation for
the subject site located in Carlsbad, California. This report presents the results of our
evaluation, discussion of our findings, and provides geotechnical recommendations for
foundation design and construction. In our opinion, site development appears feasible from a
geotechnical viewpoint provided that the recommendations included herein are incorporated
into the design and construction phases of site development.
The opportunity to be of service is sincerely appreciated. If you should have any questions,
Respectfully submitted,
Geo T ek, Inc.
__ /4d:~
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Tim 7ffiy'E. Metcalfe
CEG I 142, Exp. 04/30/ 14
Principal Geologist
Distribution: (5) Addressee
RCE 35007, Exp.
Project Engineer
GEOTECHNICAL I ENVIRONMENTAL I MATERIALS
... . /
Vesta Pacific Development
Preliminary Geotechnical Evaluation
lliil 2687 BoJ;>sev~lt Stre._et, arlsbad.,_ y ll(oJ:.D.i.il
A
I. PURPOSE AND SCOPE OF SERVICES
Project No. 3447-5D3
July 21 , 2014
Page l .:)f'" _
The purpose of this study was to evaluate the geotechnical conditions in the area of proposed
construction. Services provided for this study included the following:
► Research and review of available geologic data and general information pertinent to the
site,
► Site exploration consisting of the excavation, logging, and sampling of six (6) exploratory
borings,
► Laboratory testing of soil samples collected during the field investigation,
► Review and evaluation of site seismicity,
► Geologic and engineering analysis of data obtained, and
► Compilation of this geotechnical report which presents our findings, conclusions, and
recommendations for site development.
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
2.1 SITE DESCRIPTION / ,-).115
The site is located between 2685 and (268f'Roosevelt Street, Carlsbad, California, 92008 (see
Figure I -Site Location Map). The propeny ~ars to be rectangular elongated east to west
(perpendicular to Roosevelt). It consists of approximately 20,000 square feet of relative flat
lying terrain. The site is currently occupied by several single-and multi-family residential
buildings. There are two driveway access one servicing approximately the southern third of the
site and the second servicing the north potion of the site. The site is rather flat sloping
generally to the west with about 2 feet of fall. Surface drainage on the site appears to be
directed to the west.
The subject site is bounded by older developed sites both residential and commercial.
GEOTEK
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 9208 1-8505
(760) 599-0509 (760) 599-0593 www.geotekusa.com
Vesta Pacific Development
1818 Second Avenue
San Diego, California 920 I I
Attention:
Subject:
Mr. Geoff McComic
Infiltration Evaluation
Beachwalk at Roosevelt
2685, 2687 and 2715 Roosevelt Street
Carlsbad, California
Dear Mr. McComic:
February 27, 2016
Project No. 3447-SD3
As requested and authorized, Geo Tek, Inc. (Geo Tek) has performed an infiltration
evaluation at the subject property. The intent of this study is to estimate the infiltration
rate in the proposed infiltration area for the project site as indicated to us by Pasco,
Laret Suitor and Associates. This report presents the results of the testing completed by
GeoTek, and provides this recommendations from a geotechnical standpoint.
The subject project is located at 2685, 2687 and 2715 Roosevelt Street in Carlsbad, California.
The subject property is occupied by several old bungalow style residential structures.
Two (2) excavations were dug by hand to a depth of about 3.5 and four (4) feet foot below
existing grade in the area of the proposed storm water basins along Roosevelt Street, as
provided to Geo T ek. Percolation tests were performed in general accordance with San Diego
County DEH procedures. A 6 inch diameter test hole was manually drilled and cleaned using an
auger, the side walls were free from smeared soils, approximately 4 inches of fine gravel was
placed in the hole, A 3 inch perforated pipe was set in the hole and fine gravel placed around
the outside of the pipe. Water was then poured into the pipe to approximately 12 inches above
the gravel. Water fell to below the top of the gravel. We continued to pour additional water in
the gravel and a total of approximately 200 were used in PI without ever maintaining a head.
Approximately 35 gallons of water were used in P2. Water drained from holes completely.
Testing was performed the following day.
VESTA PACIFIC
Infiltration Evaluation
Beachwalk at Madison, Carlsbad
Project No. 3447-SDJ
February 27, 2016
Page 2
Testing (see attached) indicated a stabilized infiltration rate of approximately 3.0 gallons/hr/sf in
P2. We were unable to determine an accurate rate in PI, data suggests a rate exceeding 5.0
gallons/hr/sf. It should be realized that rates should be expected to vary and may do so
significantly.
Over the lifetime of the storm water disposal area, the infiltration rate may be affected by silt
build up and biological activities, as well as local variations in near surface soil conditions.
LIMITATIONS
The materials observed on the project site appear to be representative of the area; however,
soil 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. Geo T ek, Inc. assumes no responsibility or liability for work, testing or
recommendations performed or provided by others.
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.
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.
Attachment: Test Data
Figure I -Infiltration Test Location Map
Distribution: (I) Addressee via email (PDF file)
C E O TEK
GEOTEK, INC.
PERCOLATION TEST DATA SHEET
TEST HOLE NO. P ----------------DEPTH OF TEST HOLE: 4 ft TEST HOLE SIZE: 6inch ..,....,....-,------,-..,,.------,,----,--,----~~,---,,.,..,....,--SOIL CLASSIFICATION: Light red Brown, sl moist, clean SAND (SW)
PRESOAK PERIOD
START
STOP
TIME INTERVAL
10:50 AM
9:15 AM
2/19/16
AMOUNT OF WATER USED
200 Gallons
2/20/16 (no water left in test hole) Unable to fill hole
TEST PERIOD
Initial Water Final Water ~n Water Percolation Calculated
Time Time Interval (min) Level (inches) Level (inches) Level Rate Infiltration
(inches) (min/inch) (gal/hr/sf)
9:20 AM Attempted to fill test hole unable to obtained a 10 inch head 10:00 AM
TECHNICIAN: WO/TM DATE: 2/20/2016 ------------
TEST HOLE NO. p 2
DEPTH OF TEST HOLE: 4 ----------------S O1 L CLASSIFICATION: Red Brown, Slightly Clayey Sand, Moist (SC)
START
STOP
Time
10:20 AM
10:30 AM
10:32 AM
10:42 AM
10:45 AM
10:55 AM
10:58 AM
11 :08 AM
Roosevelt
PRESOAK PERIOD
TIME INTERVAL
11 :30 AM
10:15 AM
2/19/16
2/20/16 (no water left in test hole)
TEST PERIOD
Initial Water Final Water Time Interval (min) Level (inches) Level (inches)
10 10.0 1.9
10 10.0 1.8
10 10.0 1.8
10 10.0 1.8
TECHNICIAN: WO/TM
TEST HOLE SIZE: 6inch
AMOUNT OF WATER USED
35 Gallons
~n Water Percolation Calculated
Level Rate Infiltration
(inches) (min/inch) (gal/hr/sf)
8.1 1.2 3.0
8.2 1.2 3.1
8.2 1.2 3.1
8.2 1.2 3.1
DATE: 2/20/2016
&
Notto
Scale
Geotechnical Legend
$ Percolation Test Location
P-2
All locations approximate
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Location Map PN: 344 7-$D3 Feb 2016
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Figure 1
PRELIMINARY GEOTECHNICAL EVALUATION
FOR
PROJECT No. 3447-SDl
2685 & 2687 Roosevelt Street
MADISON STREET PROJECT
CARLSBAD, CALIFORNIA
PREPARED FOR
VESTA PACIFIC DEVELOPMENT
1818 2nd Street
SAN DIEGO, Californi a
PREPARED BY
GEOTEK, INC.
1384 POINSETTIA AVE, SUITE A
VISTA, CALIFORNIA 92081
GEOTEK
JULY 21 , 2014
GeoTek, Inc.
1384 Poinsettia Avenue, Suite A Vista, CA 92081-8505
(760) 599-0509 (760) 599-0593 www.geotekusa.com
Vesta Pacific Development
1818 Second Avenue
San Diego, California 920 I I
Attention:
Subject:
Mr. Geoff McComic
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street
Carlsbad, California
Dear Mr. McComic:
July 21, 2014
Project No. 3447-SD3
We are pleased to provide herewith the results of our preliminary geotechnical evaluation for
the subject site located in Carlsbad, California. This report presents the results of our
evaluation, discussion of our findings, and provides geotechnical recommendations for
foundation design and construction. In our opinion, site development appears feasible from a
geotechnical viewpoint provided that the recommendations included herein are incorporated
into the design and construction phases of site development.
The opportunity to be of service is sincerely appreciated. If you should have any questions,
Respectfully submitted,
GeoTek, Inc.
Distribution: (5) Addressee
RCE 35007, Exp. u.,uu,
Project Engineer
GEOTECHNICAL I ENVIRONMENTAL I MATERIALS
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street. Carlsbad. California
TABLE OF CONTENTS
Project No. 3447-SD3
July21,2014
Page i
I. PURPOSE AND SCOPE OF SERVICES ............................................................................................. I
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT .............................................................. I
2.1 SITE DESCRIPTION ................................................................................................................................................................... I
2.2 PROPOSED DEVELOPMENT ........................................................................................•............................................................ 2
3. FIELD EXPLORATION AND LABORATORY TESTING ................................................................ 2
3.1 FIELD EXPLORATION ............................................................................................................................................................... 2
3.2 LABORATORY TESTING .......................................................................................................................................................... 2
4. GEOLOGIC AND SOILS CONDITIONS ........................................................................................... 3
4.1 REGIONAL SETTING ................................................................................................................................................................ 3
4.2 GENERAL SOIL CONDITIONS ................................................................................................................................................. 4
4.3 SURFACE AND GROUNDWATER ........................................................................................................................................... 5
4.3. I Surface Water ................................................................................................................................................................................. 5
4.3.2 Groundwater .................................................................................................................................................................................... 5
4.4 FAUL TING AND SEISMICITY .................................................................................................................................................... 5
4.4. I Seismic Design Parameters ......................................................................................................................................................... 5
4.5 LIQUEFACTION AND SEISMICALLY INDUCED SETTLEMENT ................................................................................................ 6
4.6 OTHER SEISMIC HAZARDS ..................................................................................................................................................... 7
5. CONCLUSIONS AND RECOMMENDATIONS ................................................................................ 7
5.1 GENERAL .................................................................................................................................................................................. ?
5.2 EARTHWORK CONSIDERATIONS .......................................................................................................................................... ?
5.2. / Site Clearing ..................................................................................................................................................................................... 7
5.2.2 Fills ....................................................................................................................................................................................................... 8
5.2.3 Removals ........................................................................................................................................................................................... 8
5.2.4 Excavation Characteristics ........................................................................................................................................................... 8
5.2.5 Shrinkage, Bulking, and Subsidence ......................................................................................................................................... 9
5.2.6 Import Soil ........................................................................................................................................................................................ 9
5.3 DESIGN RECOMMENDATIONS ............................................................................................................................................... 9
5.3. I Foundation Design Criteria .......................................................................................................................................................... 9
5.3.2 Unders/ab Compaction Recommendations .......................................................................................................................... I I
5.3.3 Moisture and Vapor Retarding System ................................................................................................................................. 12
5.3.4 Sett/ement ....................................................................................................................................................................................... 12
5.3.5 Foundation Set Backs .................................................................................................................................................................. 12
5.3.6 Soil Corrosivity ................................................................................................................................................................................ 13
5.3. 7 Soil Sulfate Content ..................................................................................................................................................................... 13
5.4 RETAINING WALL DESIGN AND CONSTRUCTION .......................................................................................................... 13
5.4. I General Design Criteria .............................................................................................................................................................. 13
5.4.2 Cantilevered Wal/s ....................................................................................................................................................................... /4
5.4.3 Wall Back(,// and Drainage ....................................................................................................................................................... 14
5.4.4 Restrained Retaining Walls ....................................................................................................................................................... 15
5.5 POST CONSTRUCTION CONSIDERATIONS ....................................................................................................................... 15
S.S. I Landscape Maintenance and Planting ................................................................................................................................... 15
5.5.2 Drainage .......................................................................................................................................................................................... 16
5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS ................................................................................................... 16
GEOTEK
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street. Carlsbad. California
TABLE OF CONTENTS
Project No. 3447-SD3
July 21, 2014
Page ii
6. INTENT ............................................................................................................................................... 17
7. LIMITATIONS .................................................................................................................................... 17
8. SELECTED REFERENCES ................................................................................................................. 18
ENCLOSURES
Figure I -Site Location Map
Figure 2 -Site Explorations Map
Logs of Exploratory Excavations
Figure 3 -Regional Geologic Map
Appendix A -Grading Guidelines
GEOTEK
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street. Carlsbad. California
I. PURPOSE AND SCOPE OF SERVICES
Project No. 3447-SD3
July 21 , 2014
Pai:e I
The purpose of this study was to evaluate the geotechnical conditions in the area of proposed
construction. Services provided for this study included the following:
► Research and review of available geologic data and general information pertinent to the
site,
► Site exploration consisting of the excavation, logging, and sampling of six (6) exploratory
borings,
► Laboratory testing of soil samples collected during the field investigation,
► Review and evaluation of site seismicity,
► Geologic and engineering analysis of data obtained, and
► Compilation of this geotechnical report which presents our findings, conclusions, and
recommendations for site development.
2. SITE DESCRIPTION AND PROPOSED DEVELOPMENT
2.1 SITE DESCRIPTION
The site is located between 2685 and 2687 Roosevelt Street, Carlsbad, California, 92008 (see
Figure I -Site Location Map). The property appears to be rectangular elongated east to west
(perpendicular to Roosevelt). It consists of approximately 20,000 square feet of relative flat
lying terrain. The site is currently occupied by several single-and multi-family residential
buildings. There are two driveway access one servicing approximately the southern third of the
site and the second servicing the north potion of the site. The site is rather flat sloping
generally to the west with about 2 feet of fall. Surface drainage on the site appears to be
directed to the west.
The subject site is bounded by older developed sites both residential and commercial.
GEOTEK
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 2687 Roosevelt Street Carlsbad California
2.2 PROPOSED DEVELOPMENT
Project No. 3447-S03
July 2 1, 2014
Pa e 2
An undated "Conceptual Grades and Drainage Plan" prepared by Pasco Laret Suiter &
Associates was provided for our use. The Plan indicates 16 multi-family residential units are
planned for the site. Grading will elevate much of the site with drainage directed to Roosevelt
Street requiring 2150 cubic yards of import soil. This equate to about 3 feet of import fill
across the site. Retaining walls will be needed to achieve grades except along Roosevelt. It
appears the walls will not likely exceed six (6) feet in height.
We anticipate that conventionally reinforced slab-on-grade with spread and continuous wall
footings would be used to support the relatively lightweight framed structure. Structural loads
are anticipated to be typical for this type of construction, with wall loads not exceeding 3000
pounds per lineal foot and isolated columns loads not exceeding 30 kips.
If site development differs from that described above, the recommendations included in this
report should be subject to further review and evaluation.
3. FIELD EXPLORATION AND LABORATORY TESTING
3.1 FIELD EXPLORATION
Field exploration was conducted on April 23 , 2014 and June 13, 2014 and consisted of
excavating five (5) exploratory borings with a manual auger to a maximum depth of
approximately 7.5 feet. Representatives from our firm logged the excavations and collected
samples for use in the laboratory testing. The logs of exploratory borings are enclosed and the
approximate boring locations are shown on Figure 2 -Site Explorations Map.
3.2 LABORATORY TESTING
Laboratory testing was performed on selected soil samples collected during the field
exploration. The purpose of the laboratory testing was to confirm the field classification of the
soil materials encountered and to evaluate their physical properties for use in the engine ering
design and analysis. Results of the laboratory testing program, along with a brief description
and relevant information regarding testing procedures are presented below.
GEOTEK
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street, Carlsbad. California
Expansion Index
Project No. 3447-S03
July 21, 2014
Pai:e 3
Expansion Index (El) testing was performed on two soil samples. Testing was performed in
general accordance with ASTM Test Method D 4829. An El of 25 was determined for a
samples from B4 at 3 feet and an El of I 00 was determined for a sample from Bring B3 at 0 to
2 feet which indicates a low to high expansion potential of existing site soils.
Moisture-Density Relations
Laboratory testing was performed on a sample considered reasonably representative of the
dominant soil type encountered during the subsurface exploration. A laboratory maximum dry
density of 125 pd at optimum moisture content of 8.5% was determined in general accordance
with test method ASTM D 1557.
Chemical Analysis
Chemical analyses as indicated below were performed by our subcontractor. Tests results are
enclosed.
Sulfate Content
Analysis to determine the water-soluble sulfate content was performed by others in general
accordance with California Test No. 417. Results of the testing indicated a 0.018% by weight
sulfate content, which is considered "not applicable" (negligible) as per Table 4.2.1 of ACI 318.
Resistivity and pH
A representative soil sample was tested by others for resistivity and pH in general accordance
with California Test 643. The results of the testing are included herein indicate a resistivity of
3400 ohms-cm and a pH of 7.35.
Chloride
Analysis to determine the chloride content was performed by others in general accordance
with California Test No. 422. Results of the testing indicated I 02ppm.
4. GEOLOGIC AND SOILS CONDITIONS
4.1 REGIONAL SETTING
The project is situated in the Peninsular Ranges Geomorphic Province. This province
encompasses an area that extends approximately 900 miles from the Transverse Ranges south
to the tip of Baja California, and varies in width from roughly 30 to I 00 miles. The province is
characterized by mountainous terrain in the east comprised dominantly of Mesozoic igneous
GEOTEK
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Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street. Carlsbad. California
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and metamorphic rocks, with relatively low-lying coastal terraces to the west underlain by late
Cretaceous, Tertiary, and Quaternary age sedimentary bedrock.
The Peninsular Ranges are traversed by several major active faults. The Newport-Inglewood
Rose Canyon, Whittier-Elsinore, San Jacinto, and San Andreas faults are major active fault
systems located north-northeast of the site and the Rose Canyon, Coronado Bank, and San
Diego Trough are active faults located to the west. Major tectonic activity associated with
these and other faults within this regional tectonic framework is marked by right-lateral and
strike-slip movement.
The province is characterized by major mountain ranges with intervening alluviated, broadly
synclinal valleys and narrow stream canyons. The province subdivides into several individual
ranges and geologic features. The major subdivisions of interest are the Santa Ynez Mountains,
Central Ventura County Mountains, Santa Monica Mountains, Ventura/Soledad Basin, Ridge
Basin, San Gabriel Mountains, Los Angeles Basin, San Bernardino Mountains, and the Eastern
Boundary Ranges.
While the underlying geology of northern San Diego County is rather complex, in the more
immediate area of coastal north county much of the near shore terraced geomorphology is
underlain Paralic Deposits. Regional geologic mapping by Kennedy and Tan, 2005 (see Figure 3
-Regional Geologic Map) indicates this immediate area is underlain by a deposit designated as
Qop 6-7 which are relatively recent deposits.
4.2 GENERAL SOIL CONDITIONS
A brief description of the earth materials encountered is presented in the following sections.
The subsurface profile at this site consists of Quaternary old paralic deposits (see Figure 3 -
Regional Geologic Map).
Quaternary-aged old paralic deposits (formerly referred to as terrace deposits) underlie the
site at depth and generally consist of massively bedded, weakly to slightly cemented, medium
dense, sands. Approximately the upper two (2) feet is silty to clayey and loose due to
weathering. Overlying the paralic deposits in some areas are older fill soils these materials
likely date to original site development. The fills are considered not to be suitable for
structural support.
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4.3 SURFACE AND GROUNDWATER
4.3.1 Surface Water
Project No. 3447-SO3
July21,2014
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If encountered during the earthwork construction, surface water on this site is the result of
precipitation or surface run-off from surrounding site primarily to the northeast. Area
drainage is generally directed to the west. Provisions for surface drainage will need to be
accounted for by the project civil engineer, if necessary.
4.3.2 Groundwater
Groundwater was not encountered in our exploratory excavations. The site is approximately
SO feet above sea level and given the proximity to the ocean the groundwater level is probably
at least 40 feet below the surface. No natural groundwater condition is known to be present
which would impact site development. However, groundwater or localized seepage can occur
due to variations in rainfall, irrigation practices, and other factors not evident at the time of
this evaluation.
4.4 FAUL TING 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 not
situated within an "A/quist-Prio/o" Earthquake Fault Zone, or a State of California Special Studies
Zone, or any City designated zone.
4.4.1 Seismic Design Parameters
The site is located at approximately 32.1633 Latitude and -1 17.3506 Longitude. Site spectral
accelerations (Ss and SI), for 0.2 and 1.0 second periods for a risk targeted one (I) percent
probability of exceedance in SO years (MCER) were determined from the USGS
Earthquake Hazards Program, U.S. Seismic Design Maps Website
(http://earthquake.usgs.gov/designmaps/us/application.php). The site is considered a Site Class
"C", due the shallow paralic deposit. The results are presented in the following table:
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Table 4.4 -SITE SEISMIC PARAMETERS
Mapped 0.2 sec Period Spectral Acceleration, Ss (g)
Mapped 1.0 sec Period Spectral Acceleration, SI (g)
Maximum Considered Earthquake Spectral Response Acceleration
Parameter at 0.2 Second, SMS (g)
Maximum Considered Earthquake Spectral Response Acceleration
Parameter at 1.0 second, SM I (g)
Design Spectral Response Acceleration Parameter for 0.2 Second, SOS (g)
Design Spectral Response Acceleration Parameter for 1.0 Second, SD I (g)
Site Coefficient, Fa
Site Coefficient, Fv
Project No. 3447-SD3
July 21, 2014
Page 6
1.155
0.443
1.155
0.601
0.770
0.401
1.00
1.357
Seismically resistant structural design in accordance with applicable code should be followed
during the design of the structure. The California Building Code (CBC) has been developed to
reduce the potential for structural damage. However, some level of damage as the result of
ground shaking generated by nearby earthquakes is considered likely in this general area.
4.S LIQUEFACTION AND SEISMICALLY INDUCED SETTLEMENT
Liquefaction describes a phenomenon in which cyclic stresses, produced by earthquake-
induced ground motion, create excess pore pressures in relatively cohesion less soils. These
soils may thereby acquire a high degree of mobility, which can lead to lateral movement,
sliding, consolidation and settlement of loose sediments, sand boils and other damaging
deformations. This phenomenon occurs only below the water table, but, after liquefaction has
developed, it can propagate upward into overlying non-saturated soil as excess pore water
dissipates.
The factors known to influence liquefaction potential include soil type and grain size, relative
density, groundwater level, confining pressures, and both intensity and duration of ground
shaking. In general, materials that are susceptible to liquefaction are loose, saturated granular
soils having low fines content under low confining pressures.
The City of Carlsbad General Plan does not indicate the site is in a liquefaction study area.
The liquefaction potential on the site is considered negligible due to the relatively dense nature
of the underlying materials at the depths explored and expected depths to groundwater.
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4.6 OTHER SEISMIC HAZARDS
nia
Project No. 3447-SD3
July 21, 2014
7
Evidence of ancient landslides or slope instabilities at this site was not observed during our
investigation. Thus, the potential for landslides is considered negligible.
The potential for secondary seismic hazards such as seiche and tsunami are considered to be
negligible due to site elevation and distance from an open body of water.
S. CONCLUSIONSAND RECOMMENDATIONS
5.1 GENERAL
The proposed site development appears feasible from a geotechnical viewpoint provided that
the following recommendations are incorporated into the design and construction phases of
development.
Geotechnical conditions do not appear to represent significant constraints on site
development. Although relatively thick loose soil is present requiring removal and
recompaction. Import soil is planned so that the final foundation recommendations will largely
depend on the soils brought on site. Retaining walls are planned on the site perimeters, these
walls should be founded at sufficient depth to avoid imparting loads on any offsite structures.
5.2 EARTHWORK CONSIDERATIONS
Earthwork and grading should be performed in accordance with the applicable grading
ordinances of City of Carlsbad, the 2013 California Building Code (CBC), and
recommendations contained in this report. Appendix A -Grading Guidelines included in
outline general procedures and do not anticipate all site specific situations. In the event of
conflict, the recommendations presented in the text of this report should supersede those
contained in Appendix A
5.2.1 Site Clearing
The existing structure including foundations should demolished and removed from the site.
Existing landscaping and other surface improvements should be removed and properly
disposed of off-site. The site will need to be cleared including any debris present. Care should
be taken during site grading to check for any buried foundations or utilities, vegetation, roots,
trash and debris, and properly dispose of these materials offsite. Our experience is that
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abandoned septic system are present of some sites in the older sections of Carlsbad and could
be encountered during site grading. If so it would require removal. Areas of loose soil, root
systems or other undesirable items may be encountered. Any holes resulting from site
clearing, tree removal, etc. should be observed by the project geotechnical consultant prior to
filling. The voids should be filled with properly compacted fill materials with expansion
characteristics similar to the existing onsite soils.
5.2.2 Fills
The onsite soils are considered suitable for reuse as engineered fill provided they are free from
vegetation, debris and other deleterious material. Undercut areas should be brought to final
subgrade elevations with fill materials placed and compacted. Soil should be moisture
conditioned to at least optimum moisture content and compacted to a minimum of 90%
relative compaction per ASTM Test Designation 1557 in accordance with the general grading
guidelines presented in Appendix A
5.2.3 Removals
The need for removals will depend largely on the limits of existing fills and the finish site
grades. In the rear (west portion) of the site removals up to about 6 feet are expected. In
areas outside the fill removals are expected to be on the order of 3 feet. Locally deeper
removals may be encountered.
Removals should be sufficient to provide a minimum of 2 feet of engineered fill beneath the
foundation. Removal should also be sufficient to assess that all footing, utilities, etc. associated
with any prior development are removed.
Removals should extend as close to the property lines as prudent. Structural set-backs may be
warranted around the perimeter on the site.
The bottom of all removals should be scarified to an approximate depth of eight (8) inches,
brought to at or above optimum moisture content, and then recompacted to minimum project
standards prior to fill placement.
Care should be taken during removals to protect adjoining improvements. It may be necessary
to excavate small sections adjacent to the retaining walls on the adjoining properties.
5.2.4 Excavation Characteristics
Excavation in the onsite materials is expected to be easy to moderate using moderate to
heavy-duty grading equipment in good operating conditions.
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All temporary excavations for grading purposes and installation of underground utilities should
be constructed in accordance with local and Cal-OSHA guidelines. Temporary excavations
within the onsite materials are anticipated to be stable at I: I inclinations for cuts less than
seven (7) feet in height.
5.2.S Shrinkage, Bulking, and Subsidence
Several factors will impact earthwork balancing on the site, including shrinkage, bulking,
subsidence, trench spoil from utilities and footing excavations, as well as the accuracy of
topography.
Shrinkage, bulking and subsidence are primarily dependent upon the degree of compactive
effort achieved during construction. While these factors can be highly variable for planning
purposes we suggest the following be applied:
• Materials that are removed and recompacted should be anticipated to shrink
approximately IO to 20 percent.
• Compaction of removal bottoms resulting in a loose of about 0.0 I feet
• Consideration for volume of lose due to site clearing and demolition. This may be a
significant factor depending on specific conditions. For initial estimating purpose an
average lose of about 6 to 12 inches should be expected.
S.2.6 Import Soil
If import soil is needed, preferably it should have an Expansion Index (El) of 40 or less. It is
recommended that import source(s) be sampled and tested by GeoTek at least 72 hours prior
to import onto the site. Test results can then be discussed with client, who can determine
whether the materials are acceptable to them. Import materials are likely to control foundation
design and the soils chemistry at the completion of grading.
It is recommended that if possible import be obtained from a single source and be fairly
uniform in nature. If feasible the site should be brought to a relatively uniform depth from
finished grade and then import materials brought in. It would be adviseable to leave drive areas
low to accommodate footing and trench spoil rather than finding the need to export at the end
of the project.
5.3 DESIGN RECOMMENDATIONS
5.3.1 Foundation Design Criteria
Preliminary foundation design criteria for a conventional foundation system, in general
conformance with the 2013 CBC, are presented herein. These are typical design criteria and
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Preliminary Geotechnical Evaluation
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are not intended to supersede the design by the structural engineer. We have assumed that
foundations will support a minimum of two floors.
Soils encountered on site are in borings are considered to be expansive per the CBC.
However, the import soils are likely to control the final foundation design. Below are
preliminary foundation recommendations assuming soils with El ~ 40, Pl < 15. This material is
not considered to be expansive within the guidelines of the CBC. If more expansive soil is
placed beneath the foundations then modified recommendations would be required. Post-
tension foundation may be warranted in some instances. Additional laboratory testing should
be performed at the completion of site grading to verify the potential of the subgrade soils.
A summary of our preliminary foundation design recommendations are presented in Table
6.3.1 below:
TABLE 6.3.1 -MINIMUM DESIGN REQUIREMENTS
DESIGN PARAMETER O<El~40 & Pl< I 0
Foundation Depth or Minimum Perimeter Beam Supporting Two Floors -18
Depth (inches below lowest adjacent grade) Supporting Three Floors -24
Foundation Width (Inches) Supporting Two Floors -15
Supporting Three Floors -18
Minimum Slab Thickness (inches) 4 (actual)
Minimum Slab Reinforcing
No. 3 rebar 24" on-center,
placed in middle third of slab
Minimum Footing Reinforcement Four (4) No. 4 Reinforcing Bars
Two (2) top and Two (2) bottom
Presaturation of Subgrade Soil 120%/ I 2 inches
(Percent of Optimum/Depth in 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:
5.3.1.1 An allowable bearing capacity of 2000 pounds per square foot (psf) may be used for
design of continuous and perimeter footings 18 inches deep and 15 inches wide, and
pad footings 24 inches square and 24 inches deep. This value may be increased by 200
pounds per square foot for each additional 12 inches in depth and I 00 pounds per
square foot for each additional 12 inches in width to a maximum value of 3,000 psf.
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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 The passive earth pressure may be computed as an equivalent fluid having a density of
150 psf per foot of depth, to a maximum earth pressure of 2,000 psf for footings
founded on compacted fill. A coefficient of friction between soil and concrete of 0.25
may be used with dead load forces. The upper one foot of soil below the adjacent
grade should not be used in calculating passive pressure. When combining passive
pressure and frictional resistance, the passive pressure component should be reduced
by one-third.
5.3.1 .3 A grade beam, 12 inches wide by 18 inches deep (minimum), should be utilized across
large opening or garage entrances. The base of the grade beam should be at the same
elevation as the bottom of the adjoining footings.
5.3.1 .4 Isolated exterior footings should be tied back to the main foundation system in at least
one direction.
5.3.1.5 Footing excavations should be free of loose/sloughed materials and be neatly trimmed
at the time of concrete placement.
5.3.1.6 It should be noted that considering footing and other excavations may have a tendency
to slough particularly as the soil dries.
5.3.1.7 All loose material should be removed from footing prior to pouring concrete. It is
likely that this will result in additional concrete being needed.
5.3.1.8 If sides of footings are blocked out or formed to limit concrete over-pour then any
adjoining void should be properly backfilled after concrete is allowed to cure.
5.3.2 Underslab Compaction Recommendations
5.3.2.1 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.
5.3.2.2 Soils from the footing excavations should not be placed in the slab-on-grade areas
unless properly compacted and tested.
5.3.2.3 Under-slab utility trenches should be compacted to project specifications.
Compaction should be achieved with a mechanical compaction device. If backfill soils
have dried out, they should be thoroughly moisture conditioned prior to placement in
trenches.
5.3.2.4 Utility trench excavations should be shored or laid back in accordance with applicable
CAUOSHA standards.
5.3.2.5 On-site materials may not be suitable for use as bedding material, but will be suitable
as backfill. Jetting of native soils will not be acceptable.
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5.3.3 Moisture and Vapor Retarding System
Project No. 3447-SO3
July 21, 2014
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A moisture and vapor retarding system should be placed below slabs-on-grade where moisture
migration through the slab is undesirable. As a minimum, the capillary break and moisture
retarder should be in conformance with the 2013 CBC Section 1910.1 or, if adopted by the
local agency, the 20 IO California Green Building Standards Code (CALGreen) Section 4.505.2.
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 puncture
resistant than thinner ones. Products specifically designed for use as moisture/vapor retarders
may also be more puncture resistant. It is Geo T ek's opinion that a minimum IO mil thick
membrane with joints properly overlapped and sealed should be used.
Moisture and vapor retarding systems constructed in compliance with Code minimums 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. 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 Settlement
The anticipated total and differential settlements are estimated less than I inch and I /2 inch
over 40 feet of horizontal distance, respectively.
5.3.5 Foundation Set Backs
Minimum setbacks to all foundations should comply with the 2013 CBC. Any improvements
not conforming to these setbacks may be subject to lateral movements and/or differential
settlements:
♦ The outside bottom edge of all footings should be set back a minimum of H/3 (where H
is the slope height) from the face of any descending slope. The setback should be at
least 7 feet and need not exceed 40 feet.
♦ The bottom of all footings for structures near retaining walls should be deepened so as
to extend below a I: I projection upward from the bottom inside edge of the wall stem.
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♦ The bottom of any existing foundations for structures should be deepened so as to
extend below a I: I projection upward from the bottom of the nearest excavation.
♦ Structures should be setback a minimum of H/3 to a maximum of 15 feet from any
ascending slope, unless specifically reviewed and otherwise found acceptable.
5.3.6 Soil Corrosivity
The soil resistivity at this site was tested in the laboratory on representative samples collected
during the field investigation. The results of the testing indicate that the onsite soils are
considered "moderately corrosive" to buried metal in accordance with current standards
commonly used by corrosion engineers. These characteristics are considered typical of soils
commonly found in southern California. We recommend that a corrosion engineer be
consulted to provide recommendations for proper protection of buried metal at this site. It is
important to note that import soils may well control soil Corrosivity.
5.3. 7 Soil Sulfate Content
The sulfate content was determined in the laboratory for a representative onsite soil sample.
The results indicate that the water soluble sulfate range is 0.018 percent by weight, which is
considered "not applicable" (i.e. negligible) as per Table 4.2.1 of ACI 318. Concrete mix design
may be selected accordingly.
5.4 RETAINING WALL DESIGN AND CONSTRUCTION
5.4.1 General Design Criteria
Recommendations presented herein may apply to typical masonry or concrete vertical
retaining walls to a maximum height of up to 6 feet. Perimeter walls should be founded to
avoid placing any additional load on off site structures. Additional review and recommendations
should be requested for higher walls.
Retaining wall foundations, embedded a minimum of 18 inches into engineered fill or dense
paralic deposits, should be designed using an allowable bearing capacity of 2,000 psf. An
increase of one-third may be applied when considering short-term live loads (e.g. seismic and
wind loads). Bearing capacity may be increased by 200 psf for each additional foot of width or
depth to a maximum of 3,000 psf. The passive earth pressure may be computed as an
equivalent fluid having a density of 200 psf per foot of depth, to a maximum earth pressure of
2,500 psf. A coefficient of friction between soil and concrete of 0.3 may be used with dead
load forces. The upper one foot of soil below the adjacent grade should not be used in
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calculating passive pressure. When combining passive pressure and frictional resistance, the
passive pressure component should be reduced by one-third.
5.4.2 Cantilevered Walls
The recommendations presented below are for cantilevered retaining walls up to 6 feet high.
Active earth pressure may be used for retaining wall design, provided the top of the wall is not
restrained from minor deflections. An equivalent fluid pressure approach may be used to
compute the horizontal pressure against the wall. Appropriate fluid unit weights are given
below for specific slope gradients of the retained material. These do not include other
superimposed loading conditions such as traffic, structures, seismic events, or adverse geologic
conditions.
TABLE 6.4.2 -ACTIVE EARTH PRESSURES
Surface Slope of Retained Materials Equivalent Fluid Pressure Equivalent Fluid Pressure
(H:V) (PCF) (PCF)
Select Backfill* Native Backfill
Level 35 45
2:1 50 60
* Select backfill may consist of Class 2 permeable filter materials, Class 2 aggregate base or imported Sand
with an SE> 30. Backfill zone includes area between back of wall to plane (I : I, h:v) up from back of wall
foundation to ground surface.
5.4.3 Wall Backfill and Drainage
Wall backfill should include a minimum one foot wide section of 3/4 to I -inch clean crushed
rock (or approved equivalent). The rock should be placed immediately adjacent to the back of
wall and extend up from the backdrain to within approximately 12 inches of finish grade. The
upper 12 inches should consist of compacted onsite materials. Presence of other materials
might necessitate revision to the parameters provided and modification of wall designs. The
backfill materials should be placed in lifts no greater than 8-inches in thickness and compacted
at 90% relative compaction in accordance with ASTM Test Method D 1557. Proper surface
drainage needs to be provided and maintained.
Retaining walls should be provided with an adequate pipe and gravel backdrain system to
prevent build up of hydrostatic pressures. Backdrains should consist of a 4-inch diameter
perforated collector pipe (Schedule 40 PVC, SOR 35, or approved equivalent) embedded in a
minimum of one cubic foot per lineal foot of 3/4 to one inch clean crushed rock or equivalent,
wrapped in filter fabric. Panel drains may be used as an alternative. The drain system should
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Pa e 15
be connected to a suitable outlet. A minimum of two outlets should be provided for each
drain section. Spacing between drain outlets should not exceed I 00 feet.
Walls from 2 to 4 feet in height may be drained using localized gravel packs behind weep holes
at IO feet maximum spacing (e.g. approximately 1.5 cubic feet of gravel in a woven plastic bag).
Weep holes should be provided or the head joints omitted in the first course of block
extended above the ground surface. However, nuisance water may still collect in front of the
wall.
5.4.4 Restrained Retaining Walls
Any retaining walls that will be restrained prior to placing and compacting backfill material or
that have reentrant or male corners, should be designed for an at-rest equivalent fluid pressure
of 65 pcf, plus any applicable surcharge loading. For areas of male or reentrant corners, the
restrained wall design should extend a minimum distance of twice the height of the wall
laterally from the corner.
5.5 POST CONSTRUCTION CONSIDERATIONS
5.5.1 Landscape Maintenance and Planting
Water has been shown to weaken the inherent strength of soil, and slope stability is
significantly reduced by overly wet conditions. 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. An abatement program to control ground-burrowing rodents
should be implemented and maintained. This is critical as burrowing rodents can decrease the
long-term performance of slopes.
It is common for planting to be placed adjacent to structures in planter or lawn areas. This will
result in the introduction of water into the ground adjacent to the foundation. This type of
landscaping should be avoided. If used, then extreme care should be exercised with regard to
A
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the irrigation and drainage in these areas. Waterproofing of the foundation and/or subdrains
may be warranted and advisable. We could discuss these issues, if desired, when plans are
made available.
5.5.2 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 o r seep into the ground. Pad drainage should be directed toward
approved area(s) and not be blocked by other improvements.
It is the owner's responsibility to maintain and clean drainage devices on or contiguous to their
lot. In order to be effective, maintenance should be conducted on a regular and routine
schedule and necessary corrections made prior to each rainy season.
5.6 PLAN REVIEW AND CONSTRUCTION OBSERVATIONS
We recommend that site grading, specifications, and foundation plans be reviewed by this
office prior to construction to check for conformance with the recommendations of this
report. We also recommend that GeoTek representatives be present during site grading and
foundation construction to check for proper implementation of the geotechnical
recommendations. The owner/developer should have Geo T ek's representatives perform at
least the following duties:
• Observe site clearing and grubbing operations for proper removal of all 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, a construction observation and compaction report can be provided by Geo T ek,
which can comply with the requirements of the governmental agencies having jurisdiction over
the project. We recommend that these agencies be notified prior to commencement of
construction so that necessary grading permits can be obtained.
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Vesta Pacific Development
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2685 & 2687 Roosevelt Street, Carlsbad, California
6. INTENT
Project No. 3447-$D3
July 21, 2014
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It is the intent of this report to aid in the design and construction of the proposed
development. Implementation of the advice presented in Section 6 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 the area explored within the boundaries of the
subject residential lot and as shown on the enclosed Site Explorations Map (Figure 2). This
evaluation does not and should in no way be construed to encompass any areas beyond the
specific area of the proposed construction 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, our proposal (P3-0300 I I 2SD dated March
29, 2012) 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 conclusion 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.
GEOTEK
Vesta Pacific Development
Preliminary Geotechnical Evaluation
2685 & 2687 Roosevelt Street. Carlsbad. California
8. SELECTED REFERENCES
Project No. 3447-S03
July 21, 2014
Page 18
ASTM, 20 I I, "Soil and Rock: American Society for Testing and Materials," volumes 4.08 and
4.09.
California Code of Regulations, Title 24, 2013 "California Building Code,"
California Department of Water Resources groundwater well data (http://wdl.water.ca.gov).
GeoTek, Inc., In-house proprietary information.
USGS, Earthquake Hazards Program, U.S. Seismic Design Maps Website
(http://earthquake.usgs.gov/ design maps/us/application.ph p ).
City Carlsbad General Plan, obtained on City Carlsbad Web Site
(http://www.carlsbadca.gov/services/departments/planning/pages/general-plan.aspx)
GEOTEK
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1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 2014
9..::.-::..JCllll JUI O m,. 1000 MflUIS
Printed flom TOPOI C200 I Nlia,r.al Oeogitphlc Hokhrcs (WWW topo com)
Site Location Map
Roosevelt
Carlsbad, California
Figure 1
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Approximate Scale
1 inch = 35 feet
Locations are approximate
PN: 3447-$D3
1 38◄ Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 2014
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Base Map Adopted from:
"Conceptual Grades and
Drainage Plan" prepared by
Pasco Laret Suiter &
Associates
Site Exploration Plan
2685 & 2687 Roosevelt Street
Carlsbad, California
Figure 2
Logs of Exploratory Excavations
Roosevelt Street
Boring 8-1
0 -0.5' Reddish brown, hard, slightly moist, gravelly clayey Silt,
2 -5 ' Fill: variable soils types import and probably native soil, from Red brown, slightly moist,
fine to medium grained, Sand; Grey green, silty clay; brown, silty Sand
5 -6.5' Buried natural soil? Light red brown, medium stiff, slightly moist to moist, Silty clay to
clayey Silt, porous
6.5 to 7.5 Paralic deposits: Medium dense but friable, slightly moist, silty Sand to clean Sand.
Total depth 7.5'
Boring 8-2'
0 -I' Fill?: Reddish brown, hard, slightly moist, gravelly clayey Silt, porous. Refused on gravel at
12 inches
Boring moved approximately one foot
Boring B-2A
0 -1.5' Fill?: Reddish brown, hard, slightly moist, gravelly clayey Silt, porous. Refused on gravel
at 18 inches gravel may be from upper portion on hole.
Boring 8-3
0 -I' Native soil?: Reddish brown, hard, slightly moist, silty Clay, gravel at 12 inches practical
Boring moved approximately two foot
Boring 8-JA
0 -I' Native soil: Reddish brown, hard, slightly moist, silty Clay,
I to 1.5 feet transitions to clay silt then silty Sand
1.5 to 2.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand.
Boring moved approximately two foot
Boring 8-4
0 -0.5' Grass layer and abundant roots in clayey Silt
0.5 -I Native soil: Reddish brown, hard, slightly moist, clayey Silt
I to 1.5 feet transitions to clay silt then silty Sand
1.5 to 3.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand.
Boring 8-5 (planter area southern PL)
0 -0.5' Abundant organic matter in clayey Silt
0.5 -I Native soil: Reddish brown, hard, slightly moist, clayey Silt
I to 2.0 feet transitions to clay silt then silty Sand
2.0 to 3.5 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand
becomes less silty with depth.
Boring 8-6 (planter area southern PL)
0 -0.5' Abundant organic matter in clayey Silt to silty Clay
0.5 -1.5 Native soil: Reddish brown, hard, slightly moist, Silty Clay
1.5 to 2.5 feet transitions to clay silt then silty Sand
2.5 to 3.0 Paralic deposits: Medium dense but friable, slightly moist, slightly clayey to silty Sand
becomes less silty with depth.
Project No: 3447-SD3
Not to scale
il
GEOTEK
PN: 3447-SDJ
1384 Poinsettia Avenue, Suite A
Vista, California 92081-8505
July 20/4
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.
N Regional Geologic Map
Roosevelt Project
Carlsbad, California
Figure 3
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APPENDIX A
Grading Guidelines
2685 & 2687 Roosevelt Street
Carlsbad, California
Project No. 3447-SDJ
GEOTEK
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EARTHWORK GRADING GUIDELINES
EARTHWORK GRADING GUIDELINES
APPENDIXC
Page I
Site grading should be performed to at least the minimum requirements of the governing
agencies, the 2013 California Building Code and the guidelines presented below .
Site Clearing
Trees, dense vegetation, and other deleterious materials should be removed from the site.
Non organic debris or concrete may be placed in deeper fill areas per the recommendations
of the Soils Engineer.
Prudent efforts should be made by the contractor to remove all organic or other
deleterious material from the fill. This is especially important when grading is occurring near
the natural grade. All operators should be aware of these efforts. Even the most diligent
efforts may result in the incorporation of some materials. Laborers may be required as
"root pickers" .
Subdrainage
Subdrains are not anticipated in conjunction with the proposed grading. Should conditions
be encountered necessitating subdrain placement, specific recommendations will be offered.
Treatment of Existing Ground
Vegetation, rubbish and other deleterious materials should be disposed of off site .
Loose and compressible materials (including weathered rock, deposits of alluvium and
colluvium, poorly compacted or weathered fill, etc.) should be removed unless otherwise
indicated in the text of this report. Deeper removals than indicated in the text of the
report may be necessary due to saturation during winter months, as the result of changes
over time or due to variations in the subsurface .
Subsequent to removals, the ground surface should be processed to a depth of eight (8)
inches, moistened to near optimum moisture conditions and compacted to fill standards .
Exploratory test excavations (backhoe or dozer trenches) still remaining after completion of
basic removals should be excavated and filled with compacted fill if they can be located .
Fill Placement
It should be realized that proper fill compaction is largely procedural and is the responsibility
of the grading contractor. Testing and observation by the Soil Engineer, while helpful to
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EARTHWORK GRADING GUIDELINES APPENDIXC
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evaluate the efforts of the contractor, should not be considered as a substitute for proper
and consistent procedures. Compaction testing is specific to the test location; variable test
results could be obtained in other locations. Technicians typically do not see all that occurs
during construction. Deviation from the procedures found to produce adequate test results
might result in inadequate compactive efforts. The need for properly maintained equipment
and trained personnel operating it, cannot be over emphasized.
On site soil and bedrock may typically be used for compacted fill; however, some special
processing, placement or handling may be required (see report).
Material used in the compacting process should be evenly spread, moisture conditioned,
processed, and compacted in thin lifts not to exceed six (6) inches in thickness to obtain a
uniformly dense layer. The fill should be placed and compacted in nearly horizontal layers,
unless otherwise found acceptable by the Soils Engineer.
If the moisture content or relative density varies from that acceptable to the Soils Engineer,
the Contractor should rework the fill until it is in accordance with the following:
Moisture content of the fill should typically be at or above optimum moisture. Moisture
should be evenly distributed without wet and dry pockets. Pre-watering of cut or removal
areas should be considered in addition to watering during fill placement, particularly in clay
or dry surficial soils .
Each six (6) inch layer should be compacted to at least 90 percent of the maximum density
in compliance with the testing method specified by the controlling governmental agency. In
this case, the testing method is ASTM Test Designation D-1557 .
Side-hill fills should have an equipment-width key at their toe excavated through all surficial
soil and into competent material and tilted back into the hill. As the fill is elevated, it should
be benched through surficial soil and slopewash and into competent bedrock or other
material deemed suitable by the Soils Engineer .
Rock fragments less than eight (8) inches in diameter may be utilized in the fill, provided:
I. They are not placed in concentrated pockets;
2. There is a sufficient percentage of fine-grained material to surround the rocks;
3. The distribution of the rocks is observed by and acceptable to the Soils Engineer.
Rocks greater than eight (8) inches in diameter should be taken off site, or placed in
accordance with the recommendations of the Soils Engineer in areas designated as suitable
for rock disposal.
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EARTHWORK GRADING GUIDELINES APPENDIXC
Page 3
In clay soil large chunks or blocks are common; if in excess of eight (8) inches minimum
dimension then they are considered as oversized. Sheepsfoot compactors or other suitable
methods should be used to break the up blocks.
The Contractor should be required to obtain a minimum relative compaction of 90 percent
out to the finished slope face of fill slopes. This may be achieved by either overbuilding the
slope and cutting back to the compacted core, or by direct compaction of the slope face
with suitable equipment. Given the low height of slopes on this project overbuilding the
slope and cutting back to the compacted core is recommended. Other methods should be
discussed with and accepted by this firm prior to implementing .
Fill over cut slopes should be constructed in the following manner:
All surficial soils and weathered rock materials should be removed at the cut-fill interface.
This will generally result in the cut-fill catch point or daylight line being at least several feet
lower than the elevation indicated on the plans.
A key at least one (I) equipment width wide and wide enough to accommodate the method
of compaction used should be excavated into competent materials and observed by the soils
engineer or his representative. The key should be tilted into slope with the heel being at
least I foot lower in elevation than the toe.
The cut portion of the slope should be roughed out leaving the slope about three (3) feet
"fat", to evaluate if stabilization of the cut section is necessary. If the contractor decides to
place the fill prior to cut excavation, then he should be responsible for any additional
earthwork created by the fill placement and due to the need to stabilize the cut portion of
the slope.
Transition lots (cut and fill) and lots above stabilization fills should be capped with a
minimum three (3) foot thick compacted fill blanket. Deeper overexcavation may be
recommended in some cases.
Cut pads should be observed by the Engineering Geologist to evaluate the need for
overexcavation and replacement with fill. This may be necessary to reduce water infiltration
into highly fractured bedrock or other permeable zones, and/or due to differing expansive
potential of materials beneath a structure. The overexcavation should be at least three (3)
feet. Deeper overexcavation may be recommended in some cases .
In cut areas exploratory test excavations (backhoe or dozer trenches) remaining after
completion of cut excavation and removal of all surficial soils and weathered rock materials
should be excavated and filled with compacted fill if they can be located. Treatment of
borings can be determined during construction.
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EARTHWORK GRADING GUIDELINES
Grading Observation and Testing
APPENDIXC
Page 4
Observation of the fill placement should be provided by the Soils Engineer during the
progress of grading.
In general, density tests would be made at intervals not exceeding two (2) feet of fill height
or every 1,000 cubic yards of fill placed. These criteria will vary depending on soil
conditions and the size of the fill.
In any event, an adequate number of field density tests should be made to evaluate if the
compactive efforts used by the contractor are such that the required compaction and
moisture content is generally being obtained .
As proper fill compaction is largely procedural, adequate test results should not be
considered as a substitute for proper procedures. This testing is, by its nature, specific to
the test location. Variable test results could be obtained in other locations .
Density tests may be made on the surface material to receive fill, as required by the Soils
Engineer.
Cleanouts, processed ground to receive fill, key excavations, subdrains and rock disposal
areas / procedures should be observed by the Soils Engineer prior to placing any fill. It will
be the Contractor's responsibility to notify the Soils Engineer when such areas are ready for
observation .
An Engineering Geologist should observe subdrain construction .
An Engineering Geologist should observe benching prior to and during placement of fill .
!OB SAFETY
General:
Job safety is of primary concern. The following outlines safety considerations for use by all
employees on multi-employer construction sites. On ground personnel are at highest risk of
injury and possible fatality on grading construction projects. The company recognizes that
construction activities will vary on each site and that job site safety is the contractor's
responsibility. However, it is imperative that all personnel be safety conscious to avoid
accidents and potential injury .
In an effort to minimize risks associated with geotechnical testing and observation, the
following precautions are to be implemented for the safety of our field personnel on grading
and construction projects .
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Safety Meetings: Our field personnel are directed to attend the contractor's regularly
scheduled safety meetings.
Safety Vests: Safety vests are provided for and are to be worn by our personnel where
necessary.
Safety Flags: Two safety flags are provided to our field technician; one is to be affixed to the
vehicle when on site, the other is to be placed atop the spoil pile on all test pits.
In the event that our personnel do not follow the above, we request that the contractor
contact our office.
Test Pits Location, Orientation and Clearance:
The technician is responsible for selecting test pit locations. The primary concern is the
technician's safety. However, it is necessary to take sufficient tests at various locations to
obtain a representative sampling of the fill. As such, efforts will be made to coordinate
locations with the grading contractors' authorized representatives (e.g. dump man, operator,
supervisor, grade checker, etc.), and to select locations following or behind the established
traffic pattern, preferable outside of current traffic. The contractors authorized
representative should direct excavation of the pit and safety during the test period. Again,
safety is the paramount concern.
Test pits should be excavated so that the spoil pile is placed away from oncoming traffic.
The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This
necessitates that the fill be maintained in a driveable condition. Alternatively, the contractor
may opt to park a piece of equipment in front of the test pits, particularly in small fill areas
or those with limited access .
When taking slope tests, the technician should park their vehicle directly above or below
the test location on the slope. The contractor's representative should effectively keep all
equipment at a safe operation distance (e.g. 50 feet) away from the slope during testing .
The technician is directed to withdraw from the active portion of the fill as soon as possible
following testing. The technician's vehicle should be parked at the perimeter of the fill in a
highly visible location.
In the event that the technician's safety is jeopardized or compromised as a result of the
contractor's failure to comply with any of the above, the technician is directed to inform
both the developer's and contractor's representatives in writing. If the condition is not
rectified, the technician is required, by company policy, to immediately withdraw and notify
their supervisor. The grading contractor representative will then be contacted in an effort
to effect a solution. No further testing will be performed until the situation is rectified. Any
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Page 6
fill placed in the interim can be considered unacceptable and subject to reprocessing,
recompaction or removal.
In the event that the soil technician does not comply with the above or other established
safety guidelines, or if the contractor feels the technician, in any way, acts in an unsafe
manner, we request that the contractor bring this to the technicians attention and if not
rectified, notify the project manager or our office .
Effective communication and coordination between the contractors' representative and the
field technician(s) is strongly encouraged in order to implement the above safety program
and safety in general .
The safety procedures outlined above should be discussed at the contractor's safety
meetings. This will serve to inform and remind the equipment operators of these safety
procedures particularly the zone of non-encroachment .
Trench Safety:
It is the contractor's responsibility to provide safe access into trenches where compaction
testing is needed. Our personnel are directed not to enter any excavation which:
I. is 5 feet or deeper unless shored or laid back,
2. displays any evidence of instability, has any loose rock or other debris which could
fall into the trench, or
3. displays any other evidence of any unsafe conditions regardless of depth.
All utility trench excavations in excess of 5 feet deep, which a person enters, are to be
shored or laid back. Trench access should be provided in accordance with OSHA standards.
Our personnel are directed not to enter any trench by being lowered or "riding down" on
the equipment .
If the contractor fails to provide safe access to trenches for compaction testing, our
company policy requires that the soil technician withdraw and notify their supervisor. The
contractors' representative will then be contacted in an effort to effect a solution. All
backfill not tested due to safety concerns or other reasons could be subject to reprocessing
and/or removal.