HomeMy WebLinkAboutSDP 2018-0009; NORTH OAKS SELF STORAGE; FINAL SOILS REPORT; 2021-03-24FINAL REPORT OF TESTING AND
OBSERVATION SERVICES
PERFORMED DURING SITE GRADING
CARLSBAD OAKS NORTH
BUSINESS PARK – LOT 5
SDP 2018-009; GR 2019-0012; DWG 517-3A
CARLSBAD, CALIFORNIA
PREPARED FOR
WENTWORTH
PHOENIX, ARIZONA
MARCH 24, 2021
PROJECT NO. 06442-42-27B
Project No. 06442-42-27B March 24, 2021
Wentworth
802 North Third Avenue
Phoenix, Arizona, 85003
Attention: Mr. Jared Langenhuizen
Subject: FINAL REPORT OF TESTING AND OBSERVATION
SERVICES PERFORMED DURING SITE GRADING
CARLSBAD OAKS NORTH BUSINESS PARK – LOT 5
SDP 2018-009; GR 2019-0012; DWG 517-3A
CARLSBAD, CALIFORNIA
Dear Mr. Langenhuizen:
In accordance with your request, we have performed compaction testing and observation services
during grading for the subject project. We performed our services during the period of February 11,
2020 through January 4, 2021. The scope of our services included the following:
Observing the grading operation, including the removal and/or processing of soft, loose, or
accumulated soil in the existing detention basin;
Performing in-place density tests in fill placed and compacted at the site;
Performing laboratory tests to aid in evaluating maximum dry density and optimum moisture
content of the compacted fill;
Preparing an As-Graded Geologic Map; and
Preparing this final report of grading.
GENERAL
The project is located in Carlsbad Oaks North Business Park in Carlsbad, California (see Vicinity Map,
Figure 1). The site is bounded by Whiptail Loop West to the west, Faraday Avenue to the south,
Caribou Court to the north, and Lot 6 to the east. The grading contractor for the project was Sierra
Pacific West, Incorporated. Excel Engineering, the project civil engineer, prepared the project grading
plans titled Precise Grading Plan For: Carlsbad Oaks Lot 5, North Oaks Self-Storage (Whiptail Loop
West), Project No. SDP2018-0009, Drawing No. 517-3A, city approval date December 17, 2019. Geocon
Incorporated prepared the project geotechnical report titled Update Geotechnical Report, Carlsbad Oaks
North Business Park – Lot 5, SDP 2018-009: GR 2019-0012: DWG 519-3A, Carlsbad, California, dated
July 3, 2018 (Project No. 06442-42-27A).
GEOCON
INCORPORATED
G E OT E CHN I CA L ■E NV I RONMENTA L ■ MAT E RIA L S
6960 Flanders Drive ■ Son Diego, California 92121-2974 ■ Telephone 858.558.6900 ■ Fox 858.558.6159
Geocon Project No. 06442-42-27B - 2 - March 24, 2021
The base map used to present the as-graded geology and the approximate locations of the in-place
density tests (Figure 2, map pocket) was produced from a CAD file of the grading plans provided by
Excel Engineering. The map depicts slopes, building pads, and current and previous ground
topography.
References to elevations and locations presented herein are based on survey information, grade
checker stakes in the field, elevation shots taken with a Global Positioning System (GPS) unit by the
grading contractor, and interpolation from the referenced grading plan. Geocon Incorporated does not
provide surveying services and, therefore, expresses 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
The property was mass graded between July 2005 and June 2006 as part of the grading for Carlsbad Oaks
North Business Park Lots 1 through 9. Previous grading of Lot 5 was performed in conjunction with the
compaction testing and observation services by Geocon Incorporated. Test results, as well as professional
opinions pertaining to the original grading are summarized in Geocon’s as-graded report titled Final Report
of Testing & Observation Services During Site Grading, Carlsbad Oaks North Business Park – Phase 1,
Lots 1 through 9, Carlsbad, California, dated August 30, 2006 (Project No. 06442-32-04A).
Previous grading resulted in a sheet graded lot that was underlain by compacted fill and granitic rock (Kgr)
exposed at grade with ascending and descending 2:1 (horizontal:vertical) cut and fill slopes with along the
perimeter of the lot. A temporary detention basin was constructed at the southwest corner of the lot.
Recent Grading
Recent grading began with the removal of deleterious material and vegetation. Accumulated soils in
the detention basin were removed to expose competent compacted fill. Abandoned storm drain pipes
associated with the temporary basin were removed.
Areas to receive fill, including the surface of the temporary detention basin where fill was exposed,
were scarified to a depth of approximately 12 inches, moisture conditioned as necessary, and
compacted to at least 90 percent relative compaction prior to placing additional fill. In areas where
proposed cuts into existing fills were less than 12 inches, the resulting finish-grade soils were
scarified, moisture conditioned as necessary, and compacted to a minimum dry density of 90 percent
of the laboratory maximum dry density.
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After site preparation and removal of unsuitable soils as described above was performed, the site was
then brought to final subgrade elevations with structural fill compacted in layers. Layers of fill were
no thicker than would allow for adequate bonding and compaction.
Minor cuts and fills, generally less than 5 feet, were required to achieve finish grade elevations.
Approximately 7 feet of fill was placed in the temporary detention basin near the southwest corner of
Building 1.
Grading resulted in cut-to-fill transition conditions within Buildings 1 and 3. The cut portion of each
building pad was excavated approximately four feet below finish pad grade and the soil replaced with
properly compacted fill to finish grades. The undercut extended to approximately five feet
horizontally outside the limits of the building footprint area.
We observed compaction procedures and performed in-place density tests to evaluate the dry density
and moisture content of the fill. We performed in-place density tests in general conformance with
ASTM D 6938, Standard Test Method for In-Place Density and Moisture Content of Soil and Soil-
Aggregate by Nuclear Methods. The results of in-place density and moisture content tests are
presented in Table I. The locations of the tests are shown on Figure 2. In general, in-place density test
results indicate fill soils 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.
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.
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). Additionally,
we performed laboratory tests on soil samples collected near finish grade to evaluate expansion
potential (ASTM D 4829) and water-soluble sulfate content (California Test No. 417). Results of the
laboratory tests are summarized in Tables II through IV.
Finish Grade Soil Conditions
Laboratory test results and field observations indicate that the prevailing soil conditions within the
upper approximately three feet of finish pad grade have an expansion potential (EI) less than 20 and
are considered very low expansive as defined by ASTM D 4829. These soils are classified as non-
expansive (EI <20) as defined by 2019 California Building Code (CBC) Section 1803.5.3. Table 1
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presents soil classifications based on the expansion index per ASTM D 4829 and the CBC. Table III
presents a summary of expansion index test results for the prevailing soils near finish grade at the site.
TABLE 1
SOIL CLASSIFICATION BASED ON EXPANSION INDEX
ASTM D 4829
Expansion Index (EI) ASTM Expansion Classification CBC Expansion Classification
0 – 20 Very Low Non-Expansive
21 – 50 Low
Expansive 51 – 90 Medium
91 – 130 High
Greater Than 130 Very High
We performed laboratory water-soluble sulfate testing on samples obtained for expansion testing to
assess whether the soil contains sulfate concentrations known to damage normal Portland cement
concrete. 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” exposure class to concrete
structures as defined by 2019 CBC Section 1904 and ACI 318-08 Sections 4.2 and 4.3. The presence
of water-soluble sulfates is not a visually discernible characteristic; therefore, other soil samples from
the site could yield different concentrations. Additionally, over time landscaping activities (i.e.,
addition of fertilizers and other soil nutrients) may affect the concentration.
Geocon Incorporated does not practice in the field of corrosion engineering. Therefore, if
improvements that could be susceptible to corrosion are planned, further evaluation by a corrosion
engineer may be needed.
SOIL AND GEOLOGIC CONDITIONS
The soil and geologic conditions encountered during grading were found to be similar to those
described in the project geotechnical report. Compacted fill placed during previous grading and recent
grading overlies granitic rock. Granitic Rock is exposed at grade north of Building 1 and in the some
of the descending slopes around the perimeter of the site. The “As-Graded” Geologic Map, Figure 2
(map pocket), depicts the general geologic conditions observed. We did not observe soil or geologic
conditions during grading that would preclude the continued development of the property as planned.
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CONCLUSIONS AND RECOMMENDATIONS
1.0 General
1.1 Based on observations and test results, it is our opinion that grading, which is the subject of
this report, has been performed in substantial conformance with the recommendations of the
referenced project geotechnical report. Soil and geologic conditions encountered during
grading that differ from those anticipated by the project geotechnical report 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 Geocon Incorporated certifies that the soil engineering and engineering geologic aspects of the
grading are in compliance with the approved geotechnical report and the grading plan,
Drawing No. 517-3A. The term “certify” or “certification” used in this report is defined by
Section 6735.5 of the State of California Professional Engineers Act, effective January 1,
2005, which states: The use of the word "certify" or "certification" by a registered
professional engineer in the practice of professional engineering or land surveying constitutes
an expression of professional opinion regarding those facts or findings which are the subject
of certification, and does not constitute a warranty or guarantee, either expressed or implied.
1.3 No soil or geologic conditions were observed 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 soils placed during
grading operations have been compacted to at least 90 percent relative compaction.
1.4 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.
2.0 Slopes
2.1 Slope stability analyses were previously performed on the 2:1 slopes on the property for the
overall Carlsbad Oaks North Business Park development. The results of the analysis
indicate that cut and fill slopes have a factor-of-safety of at least 1.5 against deep seated and
surficial instability for the project slopes.
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2.2 No new significant fill slopes were constructed during this phase of grading.
2.3 All slopes should be landscaped with drought-tolerant vegetation that has variable root
depths and requires minimal irrigation. Irrigation should be kept to a minimum to just
support the plant growth. All slopes should be drained and properly maintained to reduce
erosion.
3.0 Seismic Design Criteria
3.1 We used the computer program U.S. Seismic Design Maps, provided by the USGS, which was
available at the time that the referenced Update Geotechnical Report was issued, to evaluate
the seismic design criteria. Table 3.1 summarizes site-specific design criteria obtained from
the 2016 California Building Code (CBC; Based on the 2015 International Building Code
[IBC] and ASCE 7-10), Chapter 16 Structural Design, Section 1613 Earthquake Loads. The
short spectral response uses a period of 0.2 second. We evaluated the Site Class based on the
discussion in Section 1613.3.2 of the 2016 CBC and Table 20.3-1 of ASCE 7-10. The values
presented in Table 3.1 are for the risk-targeted maximum considered earthquake (MCER).
TABLE 3.1
2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2016 CBC Reference
Site Class D Section 1613.2.2
MCER Ground Motion Spectral Response Acceleration – Class B (short), SS 1.037g Figure 1613.2.1(1)
MCER Ground Motion Spectral Response
Acceleration – Class B (1 sec), S1 0.403g Figure 1613.2.1(2)
Site Coefficient, FA 1.085 Table 1613.2.3(1)
Site Coefficient, FV 1.597 Table 1613.2.3(2)
Site Class Modified MCER Spectral Response Acceleration (short), SMS 1.125g Section 1613.2.3 (Eqn 16-36)
Site Class Modified MCER Spectral Response
Acceleration – (1 sec), SM1 0.643g Section 1613.2.3
(Eqn 16-37)
5% Damped Design Spectral Response Acceleration (short), SDS 0.750g Section 1613.2.4 (Eqn 16-38)
5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.429g Section 1613.2.4 (Eqn 16-39)
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.
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3.3 Table 3.2 presents additional seismic design parameters for projects located in Seismic
Design Categories D through F in accordance with ASCE 7-10 for the mapped maximum
considered geometric mean (MCEG).
TABLE 3.2
2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Site Class ASCE 7-16 Reference D
Mapped MCEG Peak Ground Acceleration, PGA 0.394g Figure 22-7
Site Coefficient, FPGA 1.106 Table 11.8-1
Site Class Modified MCEGPeak Ground Acceleration, PGAM 0.436g Section 11.8.3 (Eqn 11.8-1)
3.4 Conformance to the criteria in Tables 3.1 and 3.2 for seismic design does not constitute any
kind of guarantee or assurance that significant structural damage or ground failure will not
occur if a maximum level earthquake occurs. The primary goal of seismic design is to
protect life and not to avoid all damage, since such design may be economically prohibitive.
3.5 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. Table 3.3
presents a summary of the risk categories.
TABLE 3.3
ASCE 7-16 RISK CATEGORIES
Risk Category Building Use Examples
I Low risk to Human Life at Failure Barn, Storage Shelter
II Nominal Risk to Human Life at Failure (Buildings Not Designated as I, III or IV) Residential, Commercial and Industrial Buildings
III Substantial Risk to Human Life at Failure
Theaters, Lecture Halls, Dining Halls, Schools, Prisons, Small Healthcare Facilities, Infrastructure Plants, Storage for Explosives/Toxins
IV Essential Facilities
Hazardous Material Facilities, Hospitals, Fire and Rescue, Emergency Shelters, Police Stations, Power Stations, Aviation Control Facilities, National Defense, Water Storage
Geocon Project No. 06442-42-27B - 8 - March 24, 2021
4.0 Foundation and Concrete Slab-On-Grade Recommendations
4.1 The project is suitable for the use of continuous strip footings, isolated spread footings, or
appropriate combinations thereof, provided the preceding grading recommendations are
followed.
4.2 The following recommendations are for the planned structures and assume that the grading
will be performed as recommended in this report. Continuous footings should be at least
12 inches wide and should extend at least 24 inches below lowest adjacent pad grade and be
founded on properly compacted fill. Isolated spread footings should be at least two feet
square, extend a minimum of 24 inches below lowest adjacent pad grade, and be founded
on properly compacted fill. A typical footing dimension detail is presented on Figure 3.
4.3 The use of isolated footings, which are located beyond the perimeter of the building and
support structural elements connected to the building, are not recommended. Where this
condition cannot be avoided, isolated footings should be connected to the building
foundation system with grade beams.
4.4 The project structural engineer should design the reinforcement for the footings. For
continuous footings we recommend minimum reinforcement consisting of four No. 5 steel,
reinforcing bars, two placed near the top of the footing and two placed near the bottom. The
project structural engineer should design reinforcement of isolated spread footings.
4.5 The recommended allowable bearing capacity for foundations designed as recommended
above is 2,500 pounds per square foot (psf) for foundations in properly compacted fill soil.
This soil bearing pressure may be increased by 300 psf and 500 psf for each additional foot
of foundation width and depth, respectively, up to a maximum allowable soil bearing of
4,000 psf.
4.6 The allowable bearing pressures recommended above are for dead plus live loads only and
may be increased by up to one-third when considering transient loads such as those due to
wind or seismic forces.
4.7 The estimated maximum total and differential settlement for the planned structure due to
foundation loads is 1 inch and ¾ inch, respectively over a span of 40 feet.
4.8 Building interior concrete slabs-on-grade should be at least five inches in thickness. Slab
reinforcement should consist of No. 3 steel, bars spaced 18 inches on center in both
directions placed at the middle of the slab. If the slabs will be subjected to heavy loads,
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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.
4.9 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). The
project architect should specify the vapor retarder used based on the type of floor covering
that will be installed and if the structure will possess a humidity-controlled environment.
4.10 The bedding sand thickness should be determined by the project foundation engineer,
architect, and/or developer. However, we should be contacted to provide recommendations
if the bedding sand is thicker than 6 inches. It is common to see 3 inches of sand below a 5-
inch thick concrete slab-on-grade in the southern California area.
4.11 Exterior slabs not subject to vehicle loads should be at least 4 inches thick and reinforced
with 6x6-W2.9/W2.9 (6x6-6/6) welded-wire-mesh or No. 3 reinforcing bars spaced at
24 inches on center in both directions to reduce the potential for cracking. The
reinforcement should be placed in the middle of the slab. Proper positioning of the
reinforcement is critical to future performance of the slab. The contractor should take extra
measures to provide proper reinforcement placement.
4.12 Prior to constructing the slabs, the subgrade should be moisture conditioned to at least
optimum moisture content and compacted to a dry density of at least 90 percent of the
laboratory maximum dry density in accordance with ASTM 1557.
4.13 Crack-control joints be included in the design of concrete slabs. Crack-control joint spacing
should not exceed, in feet, twice the recommended slab thickness in inches (e.g., 10 feet by
10 feet for a 5-inch-thick slab). Crack-control joints should be created while the concrete is
still fresh using a grooving tool or shortly thereafter using saw cuts. The structural engineer
should take criteria of the American Concrete Institute into consideration when establishing
crack-control spacing patterns.
4.14 No special subgrade presaturation is deemed necessary prior to placement of concrete.
However, the slab and foundation subgrade should be moisture conditioned as necessary to
maintain a moist condition as would be expected in any concrete placement.
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4.15 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 or 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 which would permit some lateral soil
movement without causing extensive distress. Geocon Incorporated should be
consulted for specific recommendations.
4.16 The above foundation and slab-on-grade dimensions and minimum reinforcement
recommendations are based upon soil conditions only and are not intended to be used in
lieu of those required for structural purposes. The project structural engineer should design
actual concrete reinforcement.
4.17 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.
4.18 A representative of Geocon Incorporated should observe the foundation excavations prior to
the placement of reinforcing steel or concrete to check that the exposed soil conditions are
consistent with those anticipated. If unanticipated soil conditions are encountered,
foundation modifications may be required.
4.19 Geocon Incorporated should be consulted to provide additional design parameters as
required by the structural engineer.
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5.0 Retaining Wall and Lateral Load Recommendations
5.1 Retaining walls not restrained at the top and having a level backfill surface should be designed
for an active soil pressure equivalent to the pressure exerted by a fluid with a density of 35
pounds per cubic foot (pcf). Where the backfill will be inclined at 2:1 (horizontal:vertical), an
active soil pressure of 50 pcf is recommended. These soil pressures assume that the backfill
materials within an area bounded by the wall and a 1:1 plane extending upward from the base
of the wall possess an Expansion Index <50. Geocon Incorporated should be consulted for
additional recommendations if backfill materials have an EI >50.
5.2 Where walls are restrained from movement at the top, an additional uniform pressure of
8H psf (where H equals the height of the retaining wall portion of the wall in feet) should
be added to the active soil pressure where the wall possesses a height of 8 feet or less and
12H where the wall is greater than 8 feet. For retaining walls subject to vehicular loads
within a horizontal distance equal to two-thirds the wall height, a surcharge equivalent to
two feet of fill soil should be added (total unit weight of soil should be taken as 130 pcf).
5.3 Soil contemplated for use as retaining wall backfill, including import materials, should be
identified in the field prior to backfill. At that time Geocon Incorporated 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. In this regard, on-site soil to be used as
backfill may or may not meet the values for standard wall designs. 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.
5.4 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 wall designer should provide appropriate lateral deflection
quantities for planned retaining walls structures, if applicable. These lateral values should
be considered when planning types of improvements above retaining wall structures.
5.5 Retaining walls should be provided with a drainage system adequate to prevent the buildup
of hydrostatic forces and should be waterproofed as required by the project architect. The
use of drainage openings through the base of the wall (weep holes) is not recommended
where the seepage could be a nuisance or otherwise adversely affect the property adjacent
to the base of the wall. The above recommendations assume a properly compacted granular
(EI <50) free-draining backfill material with no hydrostatic forces or imposed surcharge
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load. A typical retaining wall drainage detail is presented on Figure 4. If conditions
different than those described are expected, or if specific drainage details are desired,
Geocon Incorporated should be contacted for additional recommendations.
5.6 In general, wall foundations having a minimum depth and width of one foot may be designed for
an allowable soil bearing pressure of 2,500 psf, provided the soil within three feet below the base
of the wall has an Expansion Index < 90. The recommended allowable soil bearing pressure may
be increased by 300 psf and 500 psf for each additional foot of foundation width and depth,
respectively, up to a maximum allowable soil bearing pressure of 4,000 psf.
5.7 The proximity of the foundation to the top of a slope steeper than 3:1 could impact the
allowable soil bearing pressure. Therefore, Geocon Incorporated should be consulted where
such a condition is anticipated. As a minimum, wall footings should be deepened such that
the bottom outside edge of the footing is at least seven feet from the face of slope when
located adjacent and/or at the top of descending slopes.
5.8 The structural engineer should determine the seismic design category for the project in
accordance with Section 1613 of the 2016 CBC. If the project possesses a 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 18.3.5.12 of the 2016
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) exerted at the base of the
wall and zero at the top of the wall. A seismic load of 21H should be used for design. We
used the peak ground acceleration adjusted for Site Class effects, PGAM, of 0.436g
calculated from ASCE 7-10 Section 11.8.3 and applied a pseudo-static coefficient of 0.33.
5.9 For resistance to lateral loads, a passive earth pressure equivalent to a fluid density of
300 pcf is recommended for footings or shear keys poured neat against properly compacted
granular fill soils or undisturbed formation materials. The passive pressure assumes a
horizontal surface extending away from the base of the wall at least five feet or three times
the surface generating the passive pressure, whichever is greater. The upper 12 inches of
material not protected by floor slabs or pavement should not be included in the design for
lateral resistance. Where walls are planned adjacent to and/or on descending slopes, a
passive pressure of 150 pcf should be used in design.
5.10 An ultimate friction coefficient of 0.40 may be used for resistance to sliding between soil
and concrete. This friction coefficient may be combined with the passive earth pressure
when determining resistance to lateral loads.
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5.11 The recommendations presented above are generally applicable to the design of rigid
concrete or masonry retaining walls having a maximum height of 12 feet. In the event that
walls higher than 12 feet are planned, Geocon Incorporated should be consulted for
additional recommendations.
6.0 Future Grading
6.1 Any additional grading performed at the site should be conducted in conjunction with our
observation and compaction testing services. Geocon Incorporated 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.
7.0 Slope Maintenance
7.1 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 3 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 from root growth,
soil expansion, or excavation for irrigation lines and slope planting, may also be a
significant contributing factor 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.
8.0 Site Drainage and Moisture Protection
8.1 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 2016 CBC 1804.3 or other applicable
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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.
8.2 In the case of basement walls or 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.
8.3 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.
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 on January 4, 2021. 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.
Geocon Project No. 06442-42-27B - 15 - March 24, 2021
If 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
Bradley R. Kuna
RCE 89846
Rodney C. Mikesell
GE 2533
Garry W. Cannon
CEG 2201
RCE 56468
BRK:RCM:GWC:arm
(e-mail) Addressee
SITESITE
Palomar Airport Rd
Sycam
o
r
e
A
v
e
Farada
y
A
v
e
El
Fu
e
r
t
e
S
t
NO SCALE
FIG. 1
THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH,
SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS
NOT INTENDED FOR CLIENT'S USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT
SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT
OF SUCH USE OR RELIANCE BY CLIENT.
VICINITY MAP
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
DSK/GTYPD PROJECT NO. 06442 - 42 - 27BNGB / RA
GEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:03/24/2021 8:48AM | By:RUBEN AGUILAR | File Location:Y:\PROJECTS\06442-42-27B CON-Business Park-Lot 5\DETAILS\06442-42-27B Vic Map.dwg
DATE 03 - 24 - 2021
CARLSBAD OAKS NORTH
BUSINESS PARK - LOT 5
CARLSBAD, CALIFORNIA
t
N
GEOCON
INCORPORATED
■ ■
I I
SUBDRAIN CONNECTED
TO THE CARLSBAD OAKS NORTH
BUSINESS PARK STORM DRAIN SYSTEM
331
Kgr
Kgr
Qcf/
Qcf/
Kgr
Kgr
300
312
305
327
334
329
339
329
309
304
325
336
320315
312
313
294
289
PROPOSED
BUILDING
339
339 338
339
339
336
339 338
339
338
339
Quc/
1
2
3
4
5
6
7
8
9
10
1112
13
14
25
FG-34
FG-27
FG-26
FG-33 FG-30
15
16
17
18
20
21 22
23
24
FG-28
FG-29
FG-31
FG-32FG-35
SR-36
SR-37
19
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF
PROJECT NO.
SCALE DATE
FIGURE
Plotted:03/24/2021 8:48AM | By:RUBEN AGUILAR | File Location:Y:\PROJECTS\06442-42-27B CON-Business Park-Lot 5\SHEETS\06442-42-27B GeoMap.dwg
GEOTECHNICAL ENVIRONMENTAL MATERIALS
1" =
AS - GRADED GEOLOGIC MAP
CARLSBAD OAKS NORTH
BUSINESS PARK - LOT 5
CARLSBAD, CALIFORNIA
30' 03 - 24 - 2021
06442 - 42 - 27B
1 1 2
........COMPACTED FILL
........COMPACTED FILL IN UNDERCUT AREA
........GRANITIC ROCK
(Dotted Where Buried)
........APPROX. LOCATION OF GEOLOGIC CONTACT
........APPROX. LOCATION OF IN-PLACE DENSITY TEST
FG....Finish Grade SR....Slope Repair
........APPROX. BOTTOM ELEVATION OF FILL
........APPROX. LOCATION OF EXISTING SUBDRAIN
........APPROX. ELEVATION OF EXISTING SUBDRAIN
Qcf
334
GEOCON LEGEND
Kgr
344
Quc
SR-37
CONCRETE SLAB
FOOTING*DEPTHFOOTING WIDTH*
SAND AND VAPOR
RETARDER IN
ACCORDANCE WITH ACI
FOOTING*
WIDTH
CONCRETE SLAB
PAD GRADE
FOOTING*DEPTHSAND AND VAPOR
RETARDER IN
ACCORDANCE WITH ACI
FIG. 3
WALL / COLUMN FOOTING DIMENSION DETAIL
NO SCALE
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
DSK/GTYPD PROJECT NO. 06442 - 42 - 27BNGB / RA
GEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:03/24/2021 8:48AM | By:RUBEN AGUILAR | File Location:Y:\PROJECTS\06442-42-27B CON-Business Park-Lot 5\DETAILS\Wall-Column Footing Dimension Detail (COLFOOT2).dwg
DATE 03 - 24 - 2021
CARLSBAD OAKS NORTH
BUSINESS PARK - LOT 5
CARLSBAD, CALIFORNIA
*....SEE REPORT FOR FOUNDATION WIDTH AND DEPTH RECOMMENDATION
<!·· ...
:·.' .. , .. ~ :.~ . .-....
GEOCON
INCORPORATED
■ ■
I I
PROPERLY
COMPACTED
BACKFILL
CONCRETE
BROWDITCH
2/3 H
PROPOSED
RETAINING WALL
PROPOSED
GRADE
1"
FOOTING 4" DIA. PERFORATED SCHEDULE
40 PVC PIPE EXTENDED TO
APPROVED OUTLET
MIRAFI 140N FILTER FABRIC
(OR EQUIVALENT)
1" MAX. AGGREGATE
OPEN GRADED
GROUND SURFACE
TEMPORARY BACKCUT
PER OSHA
12"
WATER PROOFING
PER ARCHITECT
H
FOOTING
PROPOSED
GRADE
4" DIA. SCHEDULE 40
PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
DRAINAGE PANEL
(MIRADRAIN 6000
OR EQUIVALENT)
RETAINING
WALL
3/4" CRUSHED ROCK
(1 CU.FT./FT.)
NOTE :
DRAIN SHOULD BE UNIFORMLY SLOPED TO GRAVITY OUTLET
OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING
CONCRETE
BROWDITCH
WATER PROOFING
PER ARCHITECT
GROUND SURFACE
12"
2/3 H 2/3 H
FOOTING
PROPOSED
GRADE
RETAINING
WALL
CONCRETE
BROWDITCH
WATER PROOFING
PER ARCHITECT
GROUND SURFACE
FILTER FABRIC
ENVELOPE
MIRAFI 140N OR
EQUIVALENT
4" DIA. SCHEDULE 40
PERFORATED PVC PIPE
OR TOTAL DRAIN
EXTENDED TO
APPROVED OUTLET
DRAINAGE PANEL
(MIRADRAIN 6000
OR EQUIVALENT)
FIG. 4
TYPICAL RETAINING WALL DRAIN DETAIL
NO SCALE
6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159
DSK/GTYPD PROJECT NO. 06442 - 42 - 27BNGB / RA
GEOTECHNICAL ENVIRONMENTAL MATERIALS
Plotted:03/24/2021 8:48AM | By:RUBEN AGUILAR | File Location:Y:\PROJECTS\06442-42-27B CON-Business Park-Lot 5\DETAILS\Typical Retaining Wall Drainage Detail (RWDD7A).dwg
DATE 03 - 24 - 2021
CARLSBAD OAKS NORTH
BUSINESS PARK - LOT 5
CARLSBAD, CALIFORNIA
GEOCON
INCORPORATED
■ ■
I I
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Project Name:Project No.:
Pre. No. Re.
1 02/11/20 Existing Basin - SW 336 1 0 129.2 8.5 120.2 10.4 93 90
2 02/11/20 Existing Basin - SW 338 1 0 129.2 8.5 124.0 9.6 96 90
3 02/11/20 Existing Basin - SW 340 1 0 129.2 8.5 120.3 10.4 93 90
4 02/12/20 East of Bldg. 2 340 1 0 129.2 8.5 124.0 9.8 96 90
5 02/12/20 Bldg 4 341 1 0 129.2 8.5 123.9 9.7 96 90
6 02/12/20 Bldg 2 341 1 0 129.2 8.5 122.4 10.2 95 90
7 02/12/20 Bldg 1 342 1 0 129.2 8.5 122.1 10.5 95 90
8 02/13/20 Bldg. 1 340 1 0 129.2 8.5 124.2 9.7 96 90
9 02/13/20 Bldg. 1 341 4 0 123.9 12.0 115.6 13.5 93 90
10 02/13/20 Bldg. 1 342 1 0 129.2 8.5 124.4 10.3 96 90
11 02/13/20 Abandoned Storm Dain 339 1 0 129.2 8.5 123.5 9.8 96 90
12 02/13/20 Abandoned Storm Dain 338 1 0 129.2 8.5 122.7 10.7 95 90
13 02/14/20 West of Bldg. 2 341 1 0 129.2 8.5 122.6 9.9 95 90
14 02/24/20 South of Bldg. 4 341 1 0 129.2 8.5 121.1 10.3 94 90
15 02/19/20 Bldg. 3 339 1 0 129.2 8.5 122.4 9.6 95 90
16 02/19/20 Bldg. 1 340 1 0 129.2 8.5 121.1 10.6 94 90
17 02/19/20 Bldg. 3 341 1 0 129.2 8.5 122.8 9.9 95 90
18 02/20/20 Bldg. 4 342 1 0 129.2 8.5 124.0 9.9 96 90
19 02/20/20 Bldg. 1, East of Elevator Pit 338 4 0 123.9 12.0 112.7 12.6 91 90
20 02/20/20 Bldg. 1 341 1 0 129.2 8.5 122.5 10.2 95 90
21 02/20/20 Bldg. 1 340 1 0 129.2 8.5 122.0 10.1 94 90
22 02/20/20 Bldg. 3 342 1 0 129.2 8.5 123.5 9.7 96 90
23 02/20/20 Bldg. 1 342 1 0 129.2 8.5 121.9 9.8 94 90
24 02/25/20 Bldg. 1 341 5 0 126.0 10.1 118.4 11.2 94 90
25 02/25/20 Bldg. 1 342 5 0 126.0 10.1 117.9 10.8 94 90
FG 26 02/26/20 Bldg. 2 343 1 0 129.2 8.5 123.2 8.9 95 90
FG 27 02/26/20 Bldg. 2 343 1 0 129.2 8.5 124.9 9.8 97 90
FG 28 02/26/20 Bldg 4 343 1 0 129.2 8.5 124.6 9.6 96 90
Required
Relative
Compaction
(%)
Curve
No.
Test No.
Carlsbad Oaks North Lot 5
Date
(MM/DD
/YY)
Elev.
or
Depth
(feet)
Location
06442-42-27B
>¾"
Rock
(%)
Max.
Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field
Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
~GEOCON
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Project Name:Project No.:
Pre. No. Re.
Required
Relative
Compaction
(%)
Curve
No.
Test No.
Carlsbad Oaks North Lot 5
Date
(MM/DD
/YY)
Elev.
or
Depth
(feet)
Location
06442-42-27B
>¾"
Rock
(%)
Max.
Dry
Density
(pcf)
Opt.
Moist
Content
(%)
Field
Dry
Density
(pcf)
Field
Moisture
Content
(%)
Relative
Compaction
(%)
FG 29 02/26/20 Bldg 4 343 1 0 129.2 8.5 123.5 9.1 96 90
FG 30 02/26/20 Bldg. 3 343 1 0 129.2 8.5 124.8 9.6 97 90
FG 31 02/26/20 Bldg. 3 343 1 0 129.2 8.5 125.8 9.0 97 90
FG 32 02/26/20 Bldg 1 343 1 0 129.2 8.5 125.4 8.8 97 90
FG 33 02/26/20 Bldg 1 343 1 0 129.2 8.5 123.1 9.9 95 90
FG 34 02/26/20 Bldg 1 343 1 0 129.2 8.5 122.7 10.1 95 90
FG 35 02/26/20 Bldg 1 343 1 0 129.2 8.5 122.4 9.4 95 90
SR 36 01/04/21 S SLOPE REPAIR 339 1 0 129.2 8.5 117.5 8.6 91 90
SR 37 01/04/21 S SLOPE REPAIR 340 1 0 129.2 8.5 116.9 8.4 90 90
~GEOCON
TABLE I
EXPLANATION OF CODED TERMS
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
>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.
TEST NO. PREFIX
TEST NO. RE.
Retest of previous density test failure following additional moisture conditioning or recompaction
Fill in area of density test was removed during construction operations
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.
ELEVATION OR DEPTH
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.
~GEOCON
Geocon Project No. 06442-42-27B March 24, 2021
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 weight)
1 Dark brown, Silty, fine SAND 129.2 8.5
4 Very dark brown, Clayey, fine to medium SAND, with trace gravel 123.9 12.0
5 Yellowish brown, fine to medium SAND (Import) 126.0 10.1
TABLE III
SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS
ASTM D 4829
Sample
No.
Representative Lots
or Buildings
Moisture Content (%) Dry
Density
(pcf)
Expansion
Index
ASTM
Classification
(per 2016 CBC)Before
Test
After
Test
EI-1 Building 2 7.4 13.8 119.6 1 Very Low
EI-2 Building 4 7.3 14.1 120.1 0 Very Low
TABLE IV
SUMMARY OF LABORATORY WATER-SOLUBLE SULFATE TEST RESULTS
CALIFORNIA TEST NO. 417
Sample No. Representative Lots
or Buildings
Water-Soluble Sulfate
(%) Sulfate Exposure Class
EI-1 Building 2 0.023 S0
EI-2 Building 4 0.003 S0