HomeMy WebLinkAboutSDP 2021-0016; CARLSBAD OAKS NORTH LOT 3; FINAL SOILS REPORT GRADING; 2025-08-29FINAL REPORT OF TESTING AND
OBSERVATION SERVICES PERFORMED
DURING GRADING
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3(DRAWING NO. 541-4A,
PROJECT NO. SDP2021-0016)
CARLSBAD, CALIFORNIA
AUGUST 28, 2025PROJECT NO. 06442-32-34A
PREPARED FOR:
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6960 Flanders Drive ■ San Diego, California 92121-2974 ■ Telephone (858) 558-6900 ■ www.geoconinc.com
Project No. 06442-32-34A
August 28, 2025
Tech Contractors
3575 Kenyon Street
San Diego, California 92110
Attention: Mr. Raul Guzman
Subject: FINAL REPORT OF TESTING AND OBSERVATION SERVICES
PERFORMED DURING GRADING
CARLSBAD OAKS NORTH BUSINESS PARK – LOT 3
(DRAWING NO. 541-4A, PROJECT NO. SDP2021-0016)
CARLSBAD, CALIFORNIA
Dear Mr. Guzman:
In accordance with your request, we have performed compaction testing and observation services
during grading of the subject project. We performed these services between July 2024 and March
2025. The scope of our services included the following:
Observing the placement of compacted fill soil during grading, including scarifying and
moisture conditioning the surface of previously compacted fill prior to placing additional fill.
Observing undercutting of the cut portion of the building pads with cut-fill transitions; as well
as undercutting of drive isles where rock was encountered in the pipe zone of select planned
underground utilities (drive isle undercut zones were determined by TFW
Construction/Development, Inc. [TFW] field representative and the grading contractor).
Performing in-place density tests in fill placed and compacted at the site.
Performing laboratory tests to aid in evaluating compaction characteristics of various soil
conditions encountered. We also performed laboratory testing on soil samples collected
during grading activities and at finish grade to evaluate direct shear strength, sieve analysis,
expansion characteristics and water-soluble sulfate content.
Preparing an as-graded geologic map.
Preparing this final report of grading.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 2 - August 28, 2025
The purpose of this report is to document that the grading has been performed in substantial
conformance with the recommendations of the project geotechnical report.
GENERAL
The Lot 3 development is located in the Carlsbad Oaks North Business Park, Carlsbad, California. The
property is bound by industrial and commercial businesses on the north, Whiptail Loop Road on the
east, and open space on the west and south (see Vicinity Map).
Vicinity Map
TFW was the general contractor for the project. F.J. Willert Contracting Company Incorporated graded
the site. Spear & Associates Incorporated, the project civil engineer, prepared the grading plans titled
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 3 - August 28, 2025
Grading Plans for: Lot 3 Whiptail Loop, Drawing No. 541-4A, Project No. SDP2021-0016, Carlsbad,
California, dated July 1, 2024. We prepared the project geotechnical reports titled:
1)Update to Geotechnical Report, Carlsbad Oaks North Business Park – Lot 3, Carlsbad, California,
prepared by Geocon Incorporated, dated May 5, 2023 (Geocon Project no. 06442-32-34).
2)Update Geotechnical Report, Carlsbad Oaks North Business Park – Lot 3, California, prepared
by Geocon Incorporated, dated May 26, 2021 (Geocon Project No. 06442-32-34).
We used an AutoCAD file of the grading plans provided by Spear & Associates as the base map (see
Figure 1) to present the as-graded geology and approximate locations of in-place density tests. The
map depicts building pads, surface parking/drive isles, slopes and, current and previous topography.
References to elevations and locations herein are based on surveyors’ or grade checkers’ stakes in the
field, information from a Global Positioning System (GPS) unit by the grading contractor, and/or
interpolation from the referenced grading plans. We do not provide surveying services; therefore, we
have no opinion regarding the accuracy of the as-graded elevations or surface geometry with respect
to the approved grading plans or proper surface drainage.
GRADING
Previous Grading
Lot 3 was sheet-graded during the Carlsbad Oaks North Business Park Phase 1 development in
conjunction with our compaction testing and observation services. Geotechnical information
pertaining to the previous grading is summarized in our geotechnical report titled Final Report of
Testing and Observation Services During Site Grading, Carlsbad Oaks North Business Park – Phase 1,
(Lots 1 through 9), Carlsbad, California, prepared by Geocon Incorporated, dated August 30, 2006
(Geocon Project No. 06442-32-04A).
Recent Grading
Grading began with removal and exportation of deleterious material and vegetation from the areas of
planned development. Within areas of planned fill across the sheet-graded pad portion of the lot, the
surface of existing compacted fill was scarified approximately 12 inches, moisture conditioned and
compacted. Prior to placing fill in the existing temporary basin, loose soils and the abandoned existing
storm drain system were removed exposing medium dense to dense compacted fill. Grading generally
consisted of cutting and filling up to approximately 5 feet to achieve design grade elevations. Fills up
to 10 feet thick was placed in the abandoned temporary basin to achieve planned grade elevations.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 4 - August 28, 2025
Grading was generally performed utilizing conventional heavy-duty grading equipment and in some
instances a rock-breaker was used to excavate the bedrock.
Where grading resulted in a bedrock-to-fill transition at grade across the building pads, the bedrock
portion was over-excavated approximately 5 feet below finish grade or 2 feet below the deepest
foundation element and replaced with properly compacted fill soil. The bottom of undercuts was
generally excavated to drain towards the drive isles or deeper fill areas. Drive isles were also undercut
where granitic rock was encountered in the pipe zone of select planned underground utilities. The
drive isle undercuts were extended at least one foot below planned utilities as confirmed by the
grading contractor. Drive isle undercut zones were determined by the TFW field representative and
the grading contractor.
FILL MATERIALS AND PLACEMENT PROCEDURES
The fill materials generally consisted of silty, fine to coarse sands with trace to few clay and boulders
generated from excavations in the existing fill and bedrock. Soil fills were placed in lifts no thicker than
would allow for adequate bonding and compaction. The soil was moisture conditioned, as necessary,
and mixed during placement. Grading resulted in compacted fill and granitic rock at grade.
Previous and recent grading resulted in an approximately 5-foot- thick soil cap containing some 6-inch-
minus rock for the building pads. A soil cap approximately 3-foot-thick containing some 6-inch-minus
rock was provided for improvement areas beyond the building pads. Fill with rock fragments up to 12
inches in size was placed below the soil cap. The original grading resulted in rocks larger than 12 inches
in diameter and generally between 2 feet and 4 feet in maximum dimension being placed at least 10
feet below previously existing finish sheet grade elevations. In some instances, larger boulders were
individually placed in the deeper fill areas. The presence of oversize rock (>6 inches) should be
expected where below-grade improvements are proposed below the soil cap. Excavations that extend
into the granitic rock may encounter highly to slightly weathered bedrock resulting in excavation
difficulty. As previously discussed, a rock breaker was used in some instances during grading to
excavate the bedrock. Oversize rock (>6 inches) may be generated in excavations performed in the
bedrock.
FIELD IN-PLACE DENSITY AND LABORATORY TESTING
We observed compaction procedures and performed in-place density tests to evaluate the dry density
and moisture content of the fill material. We performed in-place density tests in general conformance
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 5 - August 28, 2025
with ASTM D 6938, Standard Test Method for Density of Soil and Soil-Aggregate in Place by Nuclear
Methods. Table I presents the in-place dry density and moisture content tests results.
Where fill soil contained rock larger than ¾-inch, a correction was made to the laboratory maximum
dry density and optimum moisture content using methods suggested by AASHTO T224. The values of
maximum dry density and optimum moisture content presented on Table I reflect these corrections.
In general, in-place density test results indicate fill soils placed during grading have a dry density of at
least 90 percent of the laboratory maximum dry density at or slightly above optimum moisture content
at the locations tested. The approximate locations of in-place density tests taken during grading are
shown on the as-graded geologic map, Figure 1.
We performed laboratory tests on samples of soil used for fill to evaluate moisture-density
relationships, optimum moisture content, and maximum dry density (ASTM D 1557), shear strength
characteristics (AASHTO T-236) and sieve analyses (ASTM D 6913). Additionally, we performed
laboratory tests on soil samples collected near finish pad grade (soil fill cap) to evaluate expansion
potential (ASTM D 4829) and water-soluble sulfate content (California Test No. 417). Tables II through
IV present the laboratory test results. Figures 2 through 4 present the laboratory direct shear and sieve
analyses test results.
SLOPES
Slopes constructed during this and previous grading phase within the project boundary are inclined at
2:1 (horizontal:vertical) or flatter. The outer portions (the outer approximately 15 feet) of fill slopes
consist of granular soil fill predominately consisting of 6 inch minus rock and occasional rock up to 12
inches in dimension. As indicated in the project update geotechnical report, the slopes possess a factor
of safety of at least 1.5 against deep-seated and surficial failure.
All slopes should be planted and maintained to reduce erosion. Slope irrigation should be kept to a
minimum to just support the vegetative cover. Surface drainage should not be allowed to flow over
the tops of slopes.
FINISH GRADE SOIL CONDITIONS
Based on observations and laboratory test results, the prevailing soils within the upper approximately
5 feet of pad grade have an Expansion Index (EI) of 2 or less and are “non-expansive” (EI< 20) as defined
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 6 - August 28, 2025
by 2022 California Building Code (CBC) Section 1803.5.3. The following table presents soil
classifications based on the expansion index per ASTM D 4829 in accordance with the CBC. Table III
presents a summary of expansion index test results for the prevailing subgrade soils at the site.
SOIL CLASSIFICATION BASED ON EXPANSION INDEX
ASTM D 4829
Expansion Index (EI) Soil Classification
0 – 20 Very Low
21 – 50 Low
51 – 90 Medium
91 – 130 High
Greater Than 130 Very High
We performed laboratory tests on soil samples obtained for expansion testing and collected from the
building pads to evaluate the percentage of water-soluble sulfate content. Results from the laboratory
water-soluble sulfate content tests are presented in Table IV and indicate that the on-site materials at
the locations tested possess “S0” sulfate exposure to concrete structures as defined by ACI 318 Chapter
19 and in accordance with 2022 CBC Section 1904. The presence of water-soluble sulfates is not a
visually discernible characteristic; therefore, other soil samples from the site could yield different
concentrations. Additionally, landscaping activities (e.g., addition of fertilizers and other soil nutrients)
could affect the sulfate concentration over time.
We do not practice in the field of corrosion engineering. Therefore, if improvements that could be
susceptible to corrosion are planned, it is recommended that further evaluation by a corrosion
engineer be performed.
SOIL AND GEOLOGIC CONDITIONS
The soil and geologic conditions encountered during grading were found to be like those described in
the project geotechnical report. The site is underlain by compacted fill (Qcf, Quc, Qpcf) overlying
Granitic Rock (Kgr). The bedrock is also exposed at grade. Figure 1 illustrates the as-graded geologic
conditions observed during grading operations. Geologic contacts should be considered approximate.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 7 - August 28, 2025
CONCLUSIONS AND RECOMMENDATIONS
1.0 General
1.1 Based on our observations and test results, it is our opinion that grading for the Lot 3
development, which is the subject of this report, was performed in substantial conformance
with the recommendations of the project geotechnical report. Soil and geologic conditions
encountered during grading that differ from those expected are not uncommon. Where such
conditions required a significant modification to the recommendations of the project
geotechnical report, they have been described herein.
1.2 We did not observe soil or geologic conditions during grading that would preclude the
continued development of the property as planned. Based on in-place density testing,
laboratory test results, and field observations, it is our opinion that fill materials placed
during grading operations have been compacted to at least 90 percent of the laboratory
maximum dry density at or slightly above optimum moisture content.
1.3 It is not uncommon for groundwater or seepage conditions to develop where none
previously existed, particularly after landscape irrigation is initiated. The occurrence of
induced groundwater seepage from landscaping can be greatly reduced by implementing
and monitoring a landscape program that limits irrigation to that sufficient to support the
vegetative cover without overwatering. Shallow subdrains may be required in the future if
seeps occur after rainy periods or after landscaping is installed.
1.4 References to fill thickness are approximate and may be affected by subsequent fine grading
to achieve proper surface drainage.
1.5 Excavations for underground improvements could encounter and generate some rock
fragments greater than 6 inches. Excavations for improvements that extend through the 3-
foot to 5-foot-thick soil cap, such as sewer lines, may also encounter hard bedrock and rock
fragments greater than 12 inches. Excavation difficulties should be anticipated. Additionally,
rock breaking techniques or blasting may be necessary where fresh bedrock is encountered.
The potential for these conditions should be taken into consideration when determining the
type of equipment to utilize for future excavation operations.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 8 - August 28, 2025
2.0 Future Grading
2.1 Any additional grading performed at the site should be conducted in conjunction with our
observation and compaction testing services. We should review grading plans for any future
grading prior to finalizing. Trench and wall backfill should be compacted to a dry density of
at least 90 percent of the laboratory maximum dry density at or slightly above optimum
moisture content. Geocon should be notified at least 48 hours prior to commencing
additional grading or backfill operations.
3.0 Seismic Design Criteria
3.1 The following table summarizes site-specific design criteria obtained from the 2022 California
Building Code (CBC; Based on the 2021 International Building Code [IBC] and ASCE 7-16),
Chapter 16 Structural Design, Section 1613 Earthquake Loads. We used the computer program
U.S. Seismic Design Maps, provided by the Structural Engineers Association of California
(SEAOC) to calculate the seismic design parameters. The short spectral response uses a period
of 0.2 second. We evaluated the Site Class based on the discussion in Section 1613.2.2 of the
2022 CBC and Table 20.3-1 of ASCE 7-16. The values presented herein are for the risk-targeted
maximum considered earthquake (MCER). Based on soil conditions and as-graded conditions,
the planned improvements (where applicable) should be designed using a Site Class D.
2022 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2019 CBC Reference
Site Class D Section 1613.2.2
MCER Ground Motion Spectral Response Acceleration – Class B (short), SS 0.932g Figure 1613.2.1(1)
MCER Ground Motion Spectral Response Acceleration – Class B (1 sec), S1 0.342g Figure 1613.2.1(2)
Site Coefficient, FA 1.127 Table 1613.2.3(1)
Site Coefficient, FV 1.958*Table 1613.2.3(2)
Site Class Modified MCER Spectral Response Acceleration (short), SMS 1.051g Section 1613.2.3 (Eqn 16-36)
Site Class Modified MCER Spectral Response Acceleration – (1 sec), SM1 0.67g* Section 1613.2.3 (Eqn 16-37)
5% Damped DesignSpectral Response Acceleration (short), SDS 0.70g Section 1613.2.4 (Eqn 16-38)
5% Damped DesignSpectral Response Acceleration (1 sec), SD1 0.447g* Section 1613.2.4 (Eqn 16-39)
*Using the code-based values presented in this table, in lieu of a performing a ground motion hazard
analysis, requires the exceptions outlined in ASCE 7-16 Section 11.4.8 be followed by the project
structural engineer. Per Section 11.4.8 of ASCE/SEI 7-16, a ground motion hazard analysis should be
performed for projects for Site Class “E” sites with Ss greater than or equal to 1.0g and for Site Class “D”
and “E” sites with S1 greater than 0.2g; however, Section 11.4.8 also provides exceptions which indicates
that the ground motion hazard analysis may be waived provided the exceptions are followed.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 9 - August 28, 2025
3.2 The project structural engineer and architect should evaluate the appropriate Risk Category
and Seismic Design Category for the planned structures. The values presented herein
assume a Risk Category of II and resulting in a Seismic Design Category D.
3.3 The following table presents additional seismic design parameters for projects located in
Seismic Design Categories of D through F in accordance with ASCE 7-16 for the mapped
maximum considered geometric mean (MCEG).
ASCE 7-16 SEISMIC DESIGN PARAMETERS
Parameter Value, Site Class C ASCE 7-16 Reference
Site Class D Section 1613.2.2 (2019 CBC)
Mapped MCEG Peak Ground
Acceleration, PGA 0.405g Figure 22-7
Site Coefficient, FPGA 1.195 Table 11.8-1
Site Class Modified MCEG
Peak Ground Acceleration, PGAM 0.484g Section 11.8.3 (Eqn 11.8-1)
3.4 Conformance to the criteria for seismic design does not constitute any kind of guarantee or
assurance that significant structural damage or ground failure will not occur if a large
earthquake occurs. The primary goal of seismic design is to protect life, not to avoid all
damage, since such design may be economically prohibitive.
4.0 Shallow Foundation Recommendations
4.1 The project is suitable for the use of continuous strip footings, isolated spread footings, or
appropriate combinations thereof. Based on as-graded conditions, the foundations for
planned structures will bear entirely on properly compacted fill, and soil within 5 feet of
finish grade consists of very low to low expansive soils (Expansion Index <50).
4.2 The following table provides a summary of the foundation design recommendations.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 10 - August 28, 2025
SUMMARY OF FOUNDATION RECOMMENDATIONS
Parameter
Value -
Laboratory/Office Building and Parking
Garage Footings Bearing on Compacted Fill
Minimum Continuous Foundation Width 12 inches
Minimum Isolated Foundation Width 24 inches
Minimum Foundation Depth 24 Inches Below Lowest Adjacent Grade
Minimum Steel Reinforcement 4 No. 5 Bars, 2 at the Top and 2 at the Bottom
Allowable Bearing Capacity 2,500 psf
Bearing Capacity Increase 500 psf per Foot of Depth
300 psf per Foot of Width
Maximum Allowable Bearing Capacity 4,000 psf
Estimated Total Settlement 1 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
Design Expansion Index 50 or less
4.3 The foundations should be embedded in accordance with the recommendations herein and
the Wall/Column Footing Dimension Detail. The embedment depths should be measured
from the lowest adjacent pad grade for both interior and exterior footings. Footings should
be deepened such that the bottom outside edge of the footing is at least 7 feet horizontally
from the face of descending slopes.
Wall/Column Footing Dimension Detail
4.4 The bearing capacity values presented herein are for dead plus live loads and may be
increased by one-third when considering transient loads due to wind or seismic forces.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 11 - August 28, 2025
4.5 Consideration should be given to connecting patio slabs, which exceed 5 feet in width, to
the building foundation to reduce the potential for future separation to occur.
4.6 Where buildings or other improvements are planned near the top of a slope steeper than 3:1
(horizontal:vertical), special foundations and/or design considerations are recommended
due to the tendency for lateral soil movement to occur.
For fill slopes less than 20 feet high and cut slopes regardless of height, building
footings should be deepened such that the bottom outside edge of the footing is at
least 7 feet horizontally from the face of the slope.
Although other improvements, which are relatively rigid or brittle, such as concrete
flatwork or masonry walls, may experience some distress if located near the top of a
slope, it is generally not economical to mitigate this potential. It may be possible,
however, to incorporate design measures that would permit some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
4.7 We should observe the foundation excavations prior to the placement of reinforcing steel
and concrete to check that the exposed soil conditions are similar to those expected. We
also need to check that the foundation excavations have been extended to the appropriate
bearing strata. Foundation modifications may be required if unexpected soil conditions are
encountered.
4.8 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation subgrade soil should be moisturized to maintain a moist condition
as would be expected in any such concrete placement.
4.9 We should be consulted to provide additional design parameters as required by the
structural engineer.
5.0 Interior Concrete Slabs-on-Grade
5.1 Concrete slabs-on-grade for the structures should be constructed in accordance with
recommendations presented in the following table.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 12 - August 28, 2025
MINIMUM CONCRETE SLAB-ON-GRADE RECOMMENDATIONS
Parameter Buildings
Slab-On- Grade
Minimum Concrete Slab Thickness 5.0 inches
Minimum Steel Reinforcement No. 3 Bars 18 Inches on Center, Both Directions
Typical Slab Underlayment 3 to 4 Inches of Sand/Base
Design Expansion Index 50 or less
5.2 The concrete slab-on-grade recommendations are based on soil support characteristics only.
If the slabs will be subjected to heavy loads, consideration should be given to increasing the
slab thickness and reinforcement. The project structural engineer should design interior
concrete slabs-on-grade that will be subjected to heavy loading (i.e., fork lift, heavy storage
areas). Subgrade soils supporting heavy loaded slabs should be compacted to at least 95
percent relative compaction.
5.3 A vapor retarder should underlie slabs that may receive moisture-sensitive floor coverings
or may be used to store moisture-sensitive materials. The vapor retarder design should be
consistent with the guidelines presented in the American Concrete Institute’s (ACI) Guide for
Concrete Slabs that Receive Moisture-Sensitive Flooring Materials (ACI 302.2R-06). In
addition, the membrane should be installed in a manner that prevents puncture in
accordance with manufacturer’s recommendations and ASTM requirements. The project
architect or developer should specify the type of vapor retarder used based on the type of
floor covering that will be installed and if the structure will possess a humidity-controlled
environment.
5.4 The project foundation engineer, architect, and/or developer should determine the
thickness of bedding sand below the building slabs. In general, 3 to 4 inches of sand bedding
is typically used. We should be contacted to provide recommendations if the bedding sand
is thicker than 6 inches.
5.5 The structural design engineer should provide appropriate concrete mix design criteria and
curing measures to assure proper curing of the slab to reduce potential rapid moisture loss
and subsequent cracking and slab curl. The foundation design engineer should present the
concrete mix design and proper curing methods on the foundation plan. The foundation
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 13 - August 28, 2025
contractor should understand and follow the specifications presented on the foundation
plan.
5.6 Concrete flatwork should be provided with crack-control joints. The project structural
engineer should determine the spacing of the crack-control joints based upon the slab
thickness and its intended usage. American Concrete Institute (ACI) guidelines should be
taken into consideration when establishing crack-control-joint spacing.
5.7 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed slab subgrade soil should be moisturized to maintain a moist condition as would
be expected in any such concrete placement.
5.8 The recommendations of this report are intended to reduce the potential for cracking of
slabs due to expansive soil (if present), differential settlement of existing soil or soil with
varying thicknesses. However, even with the incorporation of the recommendations
presented herein, foundations, stucco walls, and slabs-on-grade placed on such conditions
may still exhibit some cracking due to soil movement and/or shrinkage. The occurrence of
concrete shrinkage cracks is independent of the supporting soil characteristics. Their
occurrence may be reduced and/or controlled by limiting the slump of the concrete, proper
concrete placement and curing, and by the placement of crack control joints at periodic
intervals, in particular, where re-entrant slab corners occur.
6.0 Retaining Walls and Lateral Loads Recommendations
6.1 Retaining walls should be designed using the values presented in the following table. Soil
with an expansion index (EI) greater than 50 should not be used as backfill material behind
retaining walls. We should be consulted to provide additional design parameters if backfill
material possess an EI greater than 50 or as required by the structural engineer.
RETAINING WALL DESIGN RECOMMENDATIONS
Parameter Value
Active Soil Pressure, A (Fluid Density, Level Backfill)35H pcf
Active Soil Pressure, A (Fluid Density, 2:1 Sloping Backfill)50H psf
Seismic Pressure, S 17H psf
At-Rest/Restrained Walls Additional Uniform Pressure (0 to 8 Feet High)7H psf
At-Rest/Restrained Walls Additional Uniform Pressure (8+ Feet High)13H psf
H equals the height of the retaining portion of the wall.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 14 - August 28, 2025
6.2 The project retaining walls should be designed as shown in the Retaining Wall Loading
Diagram.
Retaining Wall Loading Diagram
6.3 Where walls are restrained from movement at the top (at-rest condition), an additional
uniform pressure should be applied to the wall in accordance with retaining wall loading
diagram. For retaining walls subject to vehicular loads within a horizontal distance equal to
two-thirds the wall height, a surcharge equivalent to 2 feet of fill soil should be added (soil
total unit weight 130 pcf).
6.4 The structural engineer should determine the Seismic Design Category for the project in
accordance with Section 1613.2.5 of the 2022 CBC or Section 11.6 of ASCE 7-16. For
structures assigned to Seismic Design Category of D, E, or F, retaining walls that support
more than 6 feet of backfill should be designed with seismic lateral pressure in accordance
with Section 1803.5.12 of the 2022 CBC. The seismic load is dependent on the retained
height where H is the height of the wall, in feet, and the calculated loads result in pounds
per square foot (psf). We used the peak ground acceleration adjusted for Site Class effects,
PGAM, of 0.484g calculated from ASCE 7-16 Section 11.8.3 and applied a pseudo-static
coefficient of 0.33 to calculate the seismic load.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 15 - August 28, 2025
6.5 Retaining walls should be designed to ensure stability against overturning, sliding, and
excessive foundation pressure. Where a keyway is extended below the wall base with the
intent to engage passive pressure and enhance sliding stability, it is not necessary to consider
active pressure on the keyway.
6.6 Drainage openings through the base of the wall (weep holes) should not be used where the
seepage could be a nuisance or otherwise adversely affect planned and existing
improvements adjacent to the base of the wall. The recommendations herein assume a
properly compacted granular (EI ≤50) free-draining backfill material with no hydrostatic
forces or imposed surcharge load. The retaining wall should be properly drained as shown
in the Typical Retaining Wall Drainage Detail. If conditions different than those described are
expected, or if specific drainage details are desired, we should be contacted for additional
recommendations.
Typical Retaining Wall Drainage Detail
6.7 Wall foundations should be designed in accordance with recommendation presented in the
following table. The proximity of the foundation to the top of a slope steeper than 3:1 could
impact the allowable soil bearing pressure. Therefore, retaining wall foundations should be
deepened such that the bottom outside edge of the footing is at least 7 feet horizontally
from the face of the slope.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 16 - August 28, 2025
SUMMARY OF RETAINING WALL FOUNDATION RECOMMENDATIONS
Parameter Value
Minimum Retaining Wall Foundation Width 12 inches
Minimum Retaining Wall Foundation Depth 18 Inches
Minimum Steel Reinforcement Per Structural Engineer
Bearing Capacity 2,500 psf
Bearing Capacity Increase 500 psf per additional foot of footing depth
300 psf per additional foot of footing width
Maximum Bearing Capacity 4,000 psf
Estimated Total Settlement 1 Inch
Estimated Differential Settlement ½ Inch in 40 Feet
6.8 The recommendations presented herein are generally applicable to the design of rigid
concrete or masonry retaining walls. In the event that other types of walls (such as
mechanically stabilized earth [MSE] walls, soil nail walls, or soldier pile walls) are planned,
we should be consulted for additional recommendations.
6.9 Unrestrained walls will move laterally when backfilled and loading is applied. The amount of
lateral deflection is dependent on the wall height, the type of soil used for backfill, and loads
acting on the wall. The retaining walls and improvements above the retaining walls should
be designed to incorporate an appropriate amount of lateral deflection as determined by
the structural engineer.
6.10 Soil contemplated for use as retaining wall backfill, including import materials, should be
identified in the field prior to backfill. At that time, we should obtain samples for laboratory
testing to evaluate its suitability. Modified lateral earth pressures may be necessary if the
backfill soil does not meet the required expansion index or shear strength. City or regional
standard wall designs, if used, are based on a specific active lateral earth pressure and/or soil
friction angle. Geocon Incorporated should be consulted to assess the suitability of the on-site
soil for use as wall backfill if standard wall designs will be used.
7.0 Lateral Loading
7.1 The recommendations in the following table should be used for the design of footings or
shear keys to help design the proposed structures and improvements to resist lateral loads.
The allowable passive pressure assumes a horizontal surface extending at least 5 feet, or
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 17 - August 28, 2025
three times the surface generating the passive pressure, whichever is greater. The upper 12
inches of material in areas not protected by floor slabs or pavement should not be included
in design for passive resistance.
SUMMARY OF LATERAL LOAD DESIGN RECOMMENDATIONS
Parameter Value
Passive Pressure Fluid Density 300 pcf
Passive Pressure Fluid Density Adjacent to and/or on Descending Slopes 150 pcf
Coefficient of Friction (Concrete and Soil) 0.40
Coefficient of Friction (Along Vapor Barrier) 0.2 to 0.25*
* Per manufacturer’s recommendations.
7.2 The passive and frictional resistant loads can be combined for design purposes. The lateral
passive pressures may be increased by one-third when considering transient loads due to
wind or seismic forces.
8.0 Storm Water Management (Detention Bio-Basins, Bioswales, Permeable Pavers)
8.1 To minimize adverse impacts to existing or planned improvements, we recommend that the
storm water systems be provided with an impermeable liner to prevent water infiltration
and saturation of the fill soils. This recommendation is intended to reduce potential negative
impacts to surface improvements due to water infiltration. Properties downstream of the
storm water systems systems may be subjected to seeps, springs, slope instability, elevated
groundwater, movement of foundations and slabs, or other impacts as a result of water
infiltration. Saturating compacted fills typically results in induced hydraulic compression of
the fills potentially impacting adjacent surface improvements supported by the fill. Bioswale
systems located adjacent to pavements often enable water to migrate beneath pavements,
saturating subgrade soils and aggregate base, leading to pavement distress. Also, water may
enter underground utility pipe zones and impact improvements down gradient from the site.
8.2 The landscape architect should be consulted to provide the appropriate plant
recommendations. If drought resistant plants are not used, irrigation may be required.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 18 - August 28, 2025
9.0 Site Drainage and Moisture Protection
9.1 Adequate site drainage is critical to reduce the potential for differential soil movement,
erosion and subsurface seepage. Under no circumstances should water be allowed to pond
adjacent to footings. The site should be graded and maintained such that surface drainage
is directed away from structures in accordance with 2019 CBC 1804.3 or other applicable
standards. In addition, surface drainage should be directed away from the top of slopes into
swales or other controlled drainage devices. Roof and pavement drainage should be directed
into conduits that carry runoff away from the proposed structures.
9.2 In the case of building walls retaining landscaping areas, a water-proofing system should be
used on the wall and joints, and a Miradrain drainage panel (or similar) should be placed
over the waterproofing. The project architect or civil engineer should provide detailed
specifications on the plans for all waterproofing and drainage.
9.3 Underground utilities should be leak free. Utility and irrigation lines should be checked
periodically for leaks, and detected leaks should be repaired promptly. Detrimental soil
movement could occur if water is allowed to infiltrate the soil for prolonged periods of time.
9.4 Landscaping planters adjacent to paved areas are not recommended due to the potential
for surface or irrigation water to infiltrate the pavement's subgrade and base course. We
recommend that subdrains be used to collect excess irrigation water and transmit it to
drainage structures or impervious above-grade planter boxes. In addition, where
landscaping is planned adjacent to the pavement, we recommend construction of a cutoff
wall along the edge of the pavement that extends at least six inches below the bottom of
the base material.
10.0 Slope Maintenance
10.1 Slopes that are steeper than 3:1 (horizontal:vertical) may, under conditions that are both
difficult to prevent and predict, be susceptible to near surface (surficial) slope instability. The
instability is typically limited to the outer three feet of a portion of the slope and usually
does not directly impact the improvements on the pad areas above or below the slope. The
occurrence of surficial instability is more prevalent on fill slopes and is generally preceded
by a period of heavy rainfall, excessive irrigation, or the migration of subsurface seepage.
The disturbance and/or loosening of the surficial soils, as might result soil expansion, or
excavation for irrigation lines and slope planting, may also be a significant contributing factor
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 19 - August 28, 2025
to surficial instability. It is, therefore, recommended that, to the maximum extent practical:
(a) disturbed/loosened surficial soils be either removed or properly recompacted, (b)
irrigation systems be periodically inspected and maintained to eliminate leaks and excessive
irrigation, and (c) surface drains on and adjacent to slopes be periodically maintained to
preclude ponding or erosion. Although the incorporation of the above recommendations
should reduce the potential for surficial slope instability, it will not eliminate the possibility,
and, therefore, it may be necessary to rebuild or repair a portion of the project's slopes in
the future.
LIMITATIONS
The conclusions and recommendations contained herein apply only to our work with respect to
grading and represent conditions at the date of final observation in March 27, 2025. Any subsequent
grading should be done in conjunction with our observation and testing services. As used herein, the
term “observation” implies only that we observed the progress of the work with which we agreed to
be involved. Our services did not include the evaluation or identification of the potential presence of
hazardous or corrosive materials. Our conclusions and opinions as to whether the work essentially
complies with the job specifications are based on our observations, experience and test results.
Subsurface conditions, and the accuracy of tests used to measure such conditions, can vary greatly at
any time. We make no warranty, expressed or implied, except that our services were performed in
accordance with engineering principles generally accepted at this time and location.
We will accept no responsibility for any subsequent changes made to the site by others, by the
uncontrolled action of water, or by the failure of others to properly repair damages caused by the
uncontrolled action of water. It is the responsibility of owner to ensure that the information and
recommendations contained herein are brought to the attention of the architect and engineer for the
project, are incorporated into the plans, and that the necessary steps are taken to see that the
contractor and subcontractors carry out such recommendations in the field. Recommendations that
pertain to the future maintenance and care for the property should be brought to the attention of
future owners of the property or portions thereof. The findings and recommendations of this report
may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject
to review and should not be relied upon after a period of three years.
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A - 20 - August 28, 2025
Should you have any questions regarding this report, or if we may be of further service, please contact
the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
Emilio Alvarado
RCE 66915
David B. Evans
CEG 1860
EA:DBE:am
Attachments: Figures 1through 4
(e-mail) Addressee
D
D
WHIPTAIL LOOP
WHIPTAIL LOOP
3
2
0
33
0
34
0
35
0
36
0
37
0
3
1
0
3
2
0
33
0
34
0
35
0
360
3
2
5
3
1
5
31
5
32
5
33
5
34
5
355
365
36
5
35
5
34
5
33
5
BUILDING "A"
BUILDING "B"
BUILDING "C"
BIOFILTRATION BA
S
I
N
A
BIOFILTRATION BAS
I
N
B
2
2
2
2
22
2
2
22
3
1
11
1
1
3
3
3
3
3
3
3
3
1
1
1
1
1
1
1 1
1 1 1
1
1
1
1
1
1
1 1
1
1
3
3
3
3
3
4
4
4 44
4
4
4
5
5
66
6
6
6
7 7
6
6
7
ABCDE
1
2
3
A
B
C
D
3 2 1
6
3
4
Quc/
295
273
Qcf/
Qcf/
Qpcf/
Kgr
Kgr
Qcf/
PROPERTY BOUNDARY
Quc/
Quc/
Qcf/
350
343
324
304
317
304
312
299
307
296
297
284
276
270
284
298
309
312
296
299
271
290
317
317
317
317
317
317
316
316
316
316
316
316
Kgr
317
Qpcf/
Qpcf/
1
2
3
11
12
14
15
16
22
23
6
7
8
5
9
10
4
1819
20
24
26
28
29
30
31
32
33
34
35
17
25
21
27
13
36
37
38
39
40
41
42
43
44
45
46
FG-47
FG-48
59
60
61
FG-49
FG-50
51
52
53
54
55
FG-56
FG-57
FG-58
62
63
6466
7368 71
72
65
69
70
75
76
77
78
79
80
81
82
83
74
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF
PROJECT NO.
SCALE DATE
FIGURE
Plotted:08/27/2025 3:58PM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\06442-32-34A Carlsbad Oak North Business Park LOT3\SHEETS\06442-32-34A GeologicMAP.dwg
GEOTECHNICAL ENVIRONMENTAL MATERIALS
1" =
AS - GRADED GEOLOGIC 1AP
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3
CARLSBAD, CALIFORNIA
30'08 - 28 - 2025
06442 - 32 - 34A
1 1 1
252
257
GEOCON LEGEND
........COMPACTED FILLQcf
........APPROX. LOCATION OF GEOLOGIC CONTACT
........GRANITIC ROCK
(Dotted Where Buried)
Kgr
........APPROX. BOTTOM ELEVATION OF COMPACTED FILL
........APPROX. ELEVATION OF CANYON SUBDRAIN
........APPROX. LOCATION OF EXISTING CANYON SUBDRAIN
........COMPACTED FILL IN UNDERCUT AREAQuc
........APPROX. LOCATION OF IN-PLACE DENSITY TEST
(FG....Finshed Grade)
83
........PREVIOUSLY PLACED COMPACTED FILL
(See Geocon Report Dated August 30, 2006;
Geocon Project No. 06442-32-04A)
Qpcf
SAMPLE NO.: GEOLOGIC UNIT:
SAMPLE DEPTH (FT): NATURAL/REMOLDED:
1 K 2 K 4 K AVERAGE
1053.8 2261.4 4657.4 --
7.3 7.3 7.4 7.3
120.0 120.3 120.0 120.1
1 K 2 K 4 K AVERAGE
11.4 11.9 11.4 11.6
1256 2000 3623 --
1014 1932 3517 --
540
33
320
35
Figure 2
COHESION, C (PSF)
DRY DENSITY (PCF):
AFTER TEST CONDITIONS
3
ULT.-E.O.T. SHEAR STRESS (PSF):
INITIAL CONDITIONS
R
Qcf
N/A
6442-32-34A
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3
COHESION, C (PSF)
FRICTION ANGLE (DEGREES)
DIRECT SHEAR - AASHTO T-236
PROJECT NO.:
FRICTION ANGLE (DEGREES)
NORMAL STRESS TEST LOAD
ACTUAL NORMAL STRESS (PSF):
WATER CONTENT (%):
ULTIMATE
RESULTS
PEAK
NORMAL STRESS TEST LOAD
WATER CONTENT (%):
PEAK SHEAR STRESS (PSF):
0
500
1000
1500
2000
2500
3000
3500
4000
0.000 0.050 0.100 0.150 0.200 0.250 0.300
SH
E
A
R
S
T
R
E
S
S
(
P
S
F
)
HORIZONTAL DEFORMATION (IN)
1 K 2 K 4 K
1 K PEAK 2 K PEAK 4 K PEAK
1 K ULTIMATE 2 K ULTIMATE 4 K ULTIMATE
4 K
2 K
1 K
0
1000
2000
3000
4000
5000
6000
7000
0 1000 2000 3000 4000 5000 6000
SH
E
A
R
S
T
R
E
S
S
(
P
S
F
)
NORMAL STRESS (PSF)
SAMPLE NO.: GEOLOGIC UNIT:
SAMPLE DEPTH (FT): NATURAL/REMOLDED:
1 K 2 K 4 K AVERAGE
1053.8 2261.4 4657.4 --
6.6 6.9 6.6 6.7
124.1 123.7 124.1 124.0
1 K 2 K 4 K AVERAGE
10.4 10.9 10.8 10.7
995 1749 3217 --
918 1749 3217 --
350
32
270
32
Figure 3
COHESION, C (PSF)
DRY DENSITY (PCF):
AFTER TEST CONDITIONS
4
ULT.-E.O.T. SHEAR STRESS (PSF):
INITIAL CONDITIONS
R
Qcf
N/A
6442-32-34A
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3
COHESION, C (PSF)
FRICTION ANGLE (DEGREES)
DIRECT SHEAR - AASHTO T-236
PROJECT NO.:
FRICTION ANGLE (DEGREES)
NORMAL STRESS TEST LOAD
ACTUAL NORMAL STRESS (PSF):
WATER CONTENT (%):
ULTIMATE
RESULTS
PEAK
NORMAL STRESS TEST LOAD
WATER CONTENT (%):
PEAK SHEAR STRESS (PSF):
0
500
1000
1500
2000
2500
3000
3500
0.000 0.050 0.100 0.150 0.200 0.250 0.300
SH
E
A
R
S
T
R
E
S
S
(
P
S
F
)
HORIZONTAL DEFORMATION (IN)
1 K 2 K 4 K
1 K PEAK 2 K PEAK 4 K PEAK
1 K ULTIMATE 2 K ULTIMATE 4 K ULTIMATE
4 K
2 K
1 K
0
1000
2000
3000
4000
5000
6000
7000
0 1000 2000 3000 4000 5000 6000
SH
E
A
R
S
T
R
E
S
S
(
P
S
F
)
NORMAL STRESS (PSF)
Qcf
D10 (mm)D30 (mm)D60 (mm)
0.047 0.274 1.080
Figure 4
Cc
1.5
TEST DATA
SOIL DESCRIPTION
SC - Clayey SAND23.0
Cu
SIEVE ANALYSES - ASTM D 6913
CARLSBAD OAKS NORTH BUSINESS PARK - LOT 3
PROJECT NO.:
U.S. STANDARD SIEVE SIZE
6442-32-34A
SAMPLE NO.:3 GEOLOGIC UNIT:
SAMPLE DEPTH (FT.):N/A
6"5"4"3"2"
1-
1
/
2
"
1"3/
4
"
1/
2
"
3/
8
"
#4 #8 #1
0
#1
6
#2
0
#3
0
#4
0
#5
0
#6
0
#1
0
0
#2
0
0
0
10
20
30
40
50
60
70
80
90
100
0.010.11101001000
PE
R
C
E
N
T
P
A
S
S
I
N
G
PARTICLE SIZE (mm)
SAND SILT OR CLAY
COARSE FINE COARSE MEDIUM FINE
GRAVEL
Project Name:Project No.:
Pre. No. Re.
1 07/26/24 E of Bldg A-Abandoned Temp Basin 305 2 20 136.3 7.5 129.1 9.1 95 90
2 07/26/24 E of Bldg A-Abandoned Temp Basin 307 2 0 130.6 9.4 124.1 9.8 95 90
3 07/29/24 S of Bldg A 317 2 0 130.6 9.4 121.8 12.0 93 90
4 07/29/24 S of Bldg A 318 2 0 130.6 9.4 122.9 11.5 94 90
5 07/29/24 Bldg A 318 2 0 130.6 9.4 120.1 10.8 92 90
6 07/29/24 Bldg B 320 2 10 133.4 8.5 122.4 11.1 92 90
7 07/29/24 Bldg B 320 2 10 133.4 8.5 124.8 9.5 94 90
8 07/29/24 Bldg A 320 2 20 136.3 7.5 122.5 9.9 90 90
9 07/30/24 Bldg A 320 2 20 136.3 7.5 122.7 9.7 90 90
10 07/30/24 Bldg A 320 2 20 136.3 7.5 127.3 12.4 93 90
11 07/30/24 E of Bldg A-Abandoned Temp Basin 309 2 0 130.6 9.4 123.6 10.2 95 90
12 07/30/24 E of Bldg A-Abandoned Temp Basin 311 2 0 130.6 9.4 127.0 10.6 97 90
13 07/30/24 W of Bldg A Basin B 318 2 0 130.6 9.4 120.8 9.8 92 90
14 07/30/24 E of Bldg A-Abandoned Temp Basin 313 2 0 130.6 9.4 124.9 10.9 96 90
15 07/30/24 E of Bldg A-Abandoned Temp Basin 315 2 20 136.3 7.5 129.3 7.3 95 90
16 07/30/24 E of Bldg A-Abandoned Temp Basin 317 2 20 136.3 7.5 127.6 9.0 94 90
17 07/31/24 Bldg C 319 2 0 130.6 9.4 121.2 9.9 93 90
18 07/31/24 Bldg C 319 2 0 130.6 9.4 120.8 10.8 92 90
19 07/31/24 Bldg C 320 2 0 130.6 9.4 122.6 10.5 94 90
20 07/31/24 Bldg C 320 2 0 130.6 9.4 121.0 11.7 93 90
21 08/01/24 Bldg A 320 2 0 130.6 9.4 124.3 10.2 95 90
22 08/01/24 Drive Isle E of Bldg A 318 2 0 130.6 9.4 122.8 10.9 94 90
23 08/01/24 Bldg A 321 2 0 130.6 9.4 126.2 9.4 97 90
24 08/01/24 Bldg B 318 2 10 133.4 8.5 128.0 8.3 96 90
25 08/01/24 Bldg C 318 2 10 133.4 8.5 126.5 8.6 95 90
26 08/02/24 Bldg C 319 2 10 133.4 8.5 125.7 9.9 94 90
27 08/02/24 Bldg C 319 2 10 133.4 8.5 126.7 8.9 95 90
28 08/02/24 Bldg B 319 2 10 133.4 8.5 125.5 9.2 94 90
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Carlsbad Oaks North Business Park, Lot 3 06442-32-34A
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/Y
Y)
Curve
No.
>¾"
Rock
(%)
Location
Elev. or
Depth
(feet)
Max. Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Carlsbad Oaks North Business Park, Lot 3 06442-32-34A
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/Y
Y)
Curve
No.
>¾"
Rock
(%)
Location
Elev. or
Depth
(feet)
Max. Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
29 08/02/24 Bldg B 320 2 10 133.4 8.5 126.3 10.3 95 90
30 08/02/24 Bldg B 320 2 10 133.4 8.5 124.8 9.7 94 90
31 08/05/24 Bldg C 318 2 20 136.3 7.5 128.5 8.7 94 90
32 08/05/24 Bldg C 318 2 20 136.3 7.5 127.9 8.4 94 90
33 08/05/24 Bldg C 318 2 20 136.3 7.5 129.6 7.9 95 90
34 08/05/24 Bldg C 318 2 20 136.3 7.5 131.2 8.0 96 90
35 08/06/24 Bldg C 319 2 20 136.3 7.5 130.7 7.8 96 90
36 08/06/24 Bldg C 319 2 20 136.3 7.5 131.4 7.9 96 90
37 08/06/24 Bldg C 319 2 20 136.3 7.5 128.8 8.0 94 90
38 08/07/24 Bldg C 320 2 20 136.3 7.5 130.4 7.4 96 90
39 08/07/24 Bldg C 320 2 20 136.3 7.5 127.8 8.3 94 90
40 08/07/24 Bldg C 320 2 20 136.3 7.5 125.5 7.5 92 90
41 08/08/24 N of Bldg C FS OX 318 2 20 136.3 7.5 124.9 8.0 92 90
42 08/08/24 N of Bldg C FS OX 319 2 20 136.3 7.5 128.5 7.8 94 90
43 08/08/24 N of Bldg C FS OX 319 2 20 136.3 7.5 125.6 7.9 92 90
44 08/09/24 Bldg C 318 2 20 136.3 7.5 123.7 9.7 91 90
45 08/09/24 Bldg C 318 2 20 136.3 7.5 128.9 8.5 95 90
46 08/09/24 Bldg C 319 2 30 139.4 6.6 130.4 6.9 94 90
FG 47 08/09/24 Bldg A 321 2 0 130.6 9.4 126.2 9.3 97 90
FG 48 08/09/24 Bldg A 321 2 0 130.6 9.4 122.8 9.5 94 90
FG 49 08/12/24 Bldg B 322 2 10 133.4 8.5 125.2 8.5 94 90
FG 50 08/12/24 Bldg B 322 2 10 133.4 8.5 124.8 8.2 94 90
51 08/12/24 Bldg C 319 3 20 138.2 6.4 131.2 7.8 95 90
52 08/13/24 Bldg C 319 3 20 138.2 6.4 130.6 7.6 94 90
53 08/13/24 Bldg C 320 3 20 138.2 6.4 127.5 7.6 92 90
54 08/13/24 N of Bldg C FS OX 319 3 20 138.2 6.4 128.8 7.6 93 90
55 08/13/24 N of Bldg C FS OX 320 3 10 135.5 7.2 122.8 8.9 91 90
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Carlsbad Oaks North Business Park, Lot 3 06442-32-34A
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/Y
Y)
Curve
No.
>¾"
Rock
(%)
Location
Elev. or
Depth
(feet)
Max. Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
FG 56 08/13/24 Bldg C 321 3 10 135.5 7.2 122.2 8.5 90 90
FG 57 08/14/24 Bldg C 321 3 20 138.2 6.4 126.5 7.3 92 90
58 08/14/24 N of Bldg C FS OX 321 3 20 138.2 6.4 124.8 7.8 90 90
59 08/14/24 Basin E of Bldgs A & B 320 2 10 133.4 8.5 127.3 8.2 95 90
60 08/14/24 Basin E of Bldgs A & B 321 2 10 133.4 8.5 124.3 8.5 93 90
61 08/14/24 E of Bldg B 321 2 10 133.4 8.5 121.7 7.9 91 90
62 08/20/24 E of Bldg C FS OX 317 2 20 136.3 7.5 131.5 7.2 96 90
63 08/20/24 E of Bldg C FS OX 317 2 20 136.3 7.5 128.9 7.0 95 90
64 08/21/24 E of Bldg C FS OX 317 2 10 133.4 8.5 125.5 8.0 94 90
65 08/22/24 Basin E of Bldg B 320 2 20 136.3 7.5 123.7 7.6 91 90
66 08/22/24 E of Bldg C FS OX 318 2 20 136.3 7.5 127.1 7.3 93 90
67 08/23/24 Basin E of Bldg B 321 2 20 136.3 7.5 129.4 7.2 95 90
68 08/23/24 E of Bldg C FS OX 318 2 20 136.3 7.5 127.8 7.5 94 90
69 08/27/24 E of Bldg A Basin A 316 2 10 133.4 8.5 124.2 8.5 93 90
70 08/27/24 E of Bldg A Basin A 318 2 10 133.4 8.5 121.5 8.2 91 90
71 08/28/24 E of Bldg C FS OX 318 2 20 136.3 7.5 128.6 7.3 94 90
72 08/28/24 E of Bldg C FS OX 319 2 20 136.3 7.5 125.2 7.0 92 90
73 08/28/24 E of Bldg C FS OX 319 4 20 142.7 5.4 128.9 6.3 90 90
74 08/30/24 E of Bldg A Basin A 318 4 20 142.7 5.4 130.4 5.9 91 90
75 08/30/24 E of Bldg A Basin A 319 4 20 142.7 5.4 133.4 6.1 94 90
76 03/19/25 S of Bldg A 317 6 0 133.3 8.2 125.3 7.9 94 90
77 03/19/25 S of Bldg A 317 6 0 133.3 8.2 125.5 8.1 94 90
78 03/20/25 S of Bldg A 318 6 0 133.3 8.2 126.0 7.3 95 90
79 03/20/25 S of Bldg A 318 6 0 133.3 8.2 125.6 7.8 94 90
80 03/20/25 S of Bldg A 319 6 0 133.3 8.2 127.8 8.1 96 90
81 03/27/25 S of basin A 315 2 10 133.4 8.5 121.6 8.4 91 90
82 03/27/25 S of basin A 317 2 10 133.4 8.5 120.3 8.5 90 90
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Carlsbad Oaks North Business Park, Lot 3 06442-32-34A
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/Y
Y)
Curve
No.
>¾"
Rock
(%)
Location
Elev. or
Depth
(feet)
Max. Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
83 03/27/25 S of Bldg A 319 2 10 133.4 8.5 120.5 8.5 90 90
AC Asphalt Concrete IT Irrigation Trench SG Subgrade
AD Area Drain JT Joint Trench SL Sewer Lateral
B Base M Moisture Test SM Sewer Main
CG Curb/Gutter MG Minor Grading SR Slope Repair
DW Driveway MSE Mechanically Stabilized Earth Wall ST Slope Test
ET Electrical Trench PT Plumbing Trench SW Sidewalk
ETB Exploratory Trench RG Regrade SZ Slope Zone
FB Footing Backfill RWL Reclaimed Water Lateral UT Utility Trench
FG Finish Grade RWM Reclaimed Water Main WB Wall Backfill
FS Fire Service SBT Subdrain Trench WL Water Lateral
GT Gas Trench SD Storm Drain WM Water Main
A, B, C, …
R
*SC Denotes Sandcone Density Test
Corresponds to the elevation or the depth, in feet, of the in-place density/moisture content test. The value has been
rounded to the nearest whole foot.
CURVE NO.
Corresponds to the curve numbers presented in the summary of the laboratory maximum dry density and optimum
moisture content test results. The field representative selected the curve no. based on the laboratory test results and
field observations.
>¾" ROCK - ROCK CORRECTION
The laboratory maximum dry density and optimum moisture content can be adjusted for in-place soil that possesses
rock larger than ¾ inch. The curve no. is adjusted for the percentage of ¾ inch rock in accordance with ASTM D 4718 or
Woodward Clyde guidelines.
Fill in area of density test was removed during construction operations
ELEVATION OR DEPTH
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
TEST NO. - PREFIX
TEST NO. - RE.
Retest of previous density test failure following additional moisture conditioning or recompaction
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A August 28, 2025
TABLE II
SUMMARY OF LABORATORY MAXIMUM DRY DENSITY AND
OPTIMUM MOISTURE CONTENT TEST RESULTS
ASTM D 1557
Sample
No. Description
Maximum
Dry Density
(pcf)
Optimum
Moisture
Content
(% dry wt.)
1 Yellowish brown, Silty, fine to coarse SAND with little gravel
and trace clay 124.0 11.6
2 Yellowish brown to brown, Silty, fine to coarse SAND with
few to little gravel and trace clay 130.6 9.4
3 Yellowish brown to brown, Silty, fine to coarse SAND with
little gravel and few clay 132.8 8.0
4 Dark grayish brown, Silty, f-c SAND with little gravel and trace
clay (Import - ERTC) 137.7 6.8
5 Yellowish brown, Silty, fine to medium SAND with little gravel
and trace clay (Import - Ionis Pharmaceuticals Lots 21&22) 132.4 8.3
6 Yellow brown to brown, Silty, fine to medium SAND with
trace/few gravel (Import - 330 Chinquapin Ave, Carlsbad) 133.3 8.2
7 Brown, Silty, fine to medium SAND with trace gravel and
trace clay (Import - 1211 Kelly St, Oceanside) 129.5 9.1
TABLE III
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829
Sample No., Building
Pad Sampled (Range)
Moisture Content (%) Dry Density
(pcf)
Expansion
Index
Expansion
Classification Before Test After Test
EI-1
(Building A Pad)7.5 11.5 117.8 0 Very Low
EI-2
(Building B Pad) 7.5 11.3 119.1 2 Very Low
EI-3
(Building C Pad) 7.7 13.2 118.2 2 Very Low
Carlsbad Oaks North Business Park – Lot 3
Final Report of Testing and Observation Services Performed During Grading
Project No. 06442-32-34A August 28, 2025
TABLE IV
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No.* Water-Soluble Sulfate (%) Sulfate Exposure Class**
EI-1 0.002 S0
EI-2 0.008 S0
EI-3 0.014 S0
*See Table III for location.
**Reference: Table 4.2.1, ACI 318 report.
TABLE V
AS-GRADED BUILDING PAD CONDITIONS
Building No. Pad Condition
Building A Fill Pad
Building B Undercut due to Cut/Fill Transition
Building C Undercut due to Cut/Fill Transition