HomeMy WebLinkAboutCUP 2018-0023; BUENA VISTTA RESERVOIR SITE (PARK); FINAL SOILS REPORT; 2021-07-27FINAL REPORT OF TESTING AND
OBSERVATION SERVICES
PERFORMED DURING SITE GRADING
BUENA VISTA RESERVOIR SITE (PARK)
CARLSBAD, CALIFORNIA
PREPARED FOR
JULY 27, 2021
PROJECT NO. G2225-52-03
LENNAR®
Project No. G2225-52-03
July 27, 2021
Lennar Homes of California, Inc.
15131 Alton Parkway, Suite 365
Irvine, California 92618
Attention: Ms. Lisa Galloway
Subject: FINAL REPORT OF TESTING AND OBSERVATION
SERVICES PERFORMED DURING SITE GRADING
BUENA VISTA RESERVOIR SITE (PARK)
CARLSBAD, CALIFORNIA
Dear Ms. Galloway:
In accordance with our Proposal No. LG-20447 dated October 20, 2020, we provided compaction
testing and observation services during grading operations for Buena Vista Reservoir Site (Park).
The grading for the subject has been completed and is the subject of this report. We provided our
services from December 9, 2020 through June 24, 2021. We began observing removals of concrete
within the upper 3 feet of the existing reservoir basin area on December 9, 2020 and started in-place
density testing during compaction of fill on January 7, 2021. The scope of our services included:
Observing removal excavations during remedial grading operations, performing field mapping, and providing geotechnical engineering consultation services during remedial grading operations.
Observing perforation of concrete left in place at bottom of existing reservoir basin.
Performing in-place density tests on fill placed and compacted at the site during grading operations.
Performing laboratory tests to aid in evaluating the maximum dry density and optimum moisture content of the compacted fill.
Preparing an As-Graded Geologic Map.
Preparing this final report of grading.
GENERAL
The purpose of this report is to document that the grading for the Buena Vista Reservoir Site has been
performed in substantial conformance with the recommendations of the project geotechnical report.
The site is located on the south side of Buena Vista Way, east of Highland Drive, west of Valley Street
GEOCON
INCORPORATED
G E OT E CHN I CAL ■E NV I RONMENTA L ■ MA T ER I A L S
6960 Flanders Drive ■ Son Diego, California 92121-297 4 ■ Telephone 858.558.6900 ■ Fax 858.558.6159
Geocon Project No. G2225-52-03 - 2 - July 27, 2021
and north of Newland Court in Carlsbad, California (see Vicinity Map). The fill materials have been
properly placed and compacted during grading operations in conformance with the geotechnical
recommendations provided in the referenced report.
Vicinity Map
To aid in preparing this report, we reviewed the following referenced report and plans associated with
the project.
1.Update Geotechnical Investigation, Buena Vista Reservoir Site, Carlsbad, California,
prepared by Geocon Incorporated, dated December 18, 2019 (Project No. G2225-52-01).
2.Grading Plans for: Buena Vista Reservoir Site, City of Carlsbad, California, prepared by
Schmidt Design Group and Latitude 33 Planning and Engineering, approval dated
September 10, 2020 (Drawing No. 521-1A).
The grading for the project was performed by Bighorn Grading. References to elevations and locations
herein were based on surveyor’s or grade checker’s stakes in the field and interpolation from the
referenced plans. Geocon Incorporated did not provide surveying services and, therefore, has no opinion
regarding the accuracy of the elevations or surface geometry with respect to the approved plans.
GRADING OPERATIONS
The grading operations began with the removal of concrete from an existing reservoir within 3 feet of
proposed finish grade. Per our recommendations, concrete from the sides of the existing reservoir basin that
was deeper than 3 feet below proposed finish grades and supported on Old Paralic Deposits was left in
place. The concrete slab at the bottom of the reservoir was removed where there was less than 18 inches of
cover below proposed finish grade. The concrete slab left in place at the bottom of the reservoir was
Geocon Project No. G2225-52-03 - 3 - July 27, 2021
perforated by using a breaker to create holes at least 4 inches in diameter at about 10 feet on center in both
directions. During grading operations, the existing undocumented fill was removed from across the site to
expose dense Old Paralic Deposits. The removals generally extended from 1 to 2 feet deep at the western
edge of the site to approximately 3 feet deep at the eastern edge of the site.
Per our recommendations, concrete generated from the partial demolition of the reservoir was broken up
into pieces with a maximum size of 12 inches and mixed with at least 40 percent on-site sandy soils within
3 feet of finish grade. Larger concrete pieces were individually placed at the bottom of the reservoir, so that
soil could be properly compacted around the larger pieces, under the observation of our field technician.
During remedial grading operations, we observed compaction procedures and performed in-place
density tests to evaluate the dry density and moisture content of the fill material. We performed the in-
place density tests in general conformance with ASTM Test Method D 6938. Table I presents the
results of the in-place dry density tests for the site. In general, the in-place density test results indicate
that the fill soil has a dry density of at least 90 percent of the laboratory maximum dry density near to
slightly above its optimum moisture content at the locations tested. The As-Graded Geologic Map,
Figure 1, presents the approximate locations of the in-place density tests for the site.
We performed laboratory tests on soil samples used for fill to evaluate moisture-density relationships,
optimum moisture content and maximum dry density (ASTM D 1557). We also obtained samples
used to evaluate the expansion index (ASTM D 4829) and water-soluble sulfate content (California
Test No. 417) characteristics. Tables II through IV summarize the results of the laboratory tests.
SOIL AND GEOLOGIC CONDITIONS
The soil and geologic conditions encountered during grading are similar to those described in the project
geotechnical report. In general, the placement of compacted fill across the site was performed in
accordance with recommendations provided in the project geotechnical report. The As-Graded Geologic
Map, Figure 1, depicts the general geologic conditions observed. The site is underlain by recently
compacted fill overlying Old Paralic Deposits (Qop). Some existing undocumented fill (Qudf) remains in
place in the northern and northeastern portion of the site where and existing water tank and existing
pressure reducing station are located. In general, the compacted fill consists of silty sand.
CONCLUSIONS AND RECOMMENDATIONS
1.0 General
1.1 Based on observations and test results, we opine the grading to which this report pertains
has been performed in conformance with the recommendations of the previously referenced
project soils report by Geocon Incorporated, dated December 18, 2019, and the geotechnical
requirements of the grading plans.
Geocon Project No. G2225-52-03 - 4 - July 27, 2021
1.2 We did not observe soil or geologic conditions during grading that would preclude the
continued development of the property as planned.
1.3 The site is underlain by compacted fill overlying formational Old Paralic Deposits. We
observed the placement of compacted fill during remedial grading operations and performed
in-place density tests to evaluate the dry density and moisture content of the fill material.
1.4 We performed in-place dry density and moisture content testing during grading operations.
Table I presents the results of the in-place dry density/moisture content test results. In
general, the in-place density test results indicate that the fill at the locations tested has a dry
density of at least 90 percent of the laboratory maximum dry density near to slightly above
optimum moisture content at the locations tested in accordance with ASTM D 1557.
1.5 Excavations within the fill should generally be possible with moderate to heavy effort using
conventional heavy-duty equipment. Excavations deeper than 3 feet may encounter the
concrete left in place from the previous reservoir or concrete placed within the fill materials.
1.6 We understand the structures were designed using the 2016 California Building Code
(CBC). We should be contacted to provide updated recommendations for the 2019 CBC, if
necessary.
2.0 Finish Grade Soil Conditions
2.1 Observations and laboratory test results indicate that the prevailing soil conditions within
the upper approximately 3 feet of existing grades is considered to be “non-expansive”
(expansion index [EI] of less than 20) as defined by 2016 California Building Code (CBC)
Section 1803.5.3. Table 2.1 presents soil classifications based on the expansion index. We
expect a majority of the soil encountered within the upper 3 feet across the site possess a
“very low” expansion potential (EI of 20 or less).
TABLE 2.1 EXPANSION CLASSIFICATION BASED ON EXPANSION INDEX
Expansion Index (EI) ASTM D 4829 Expansion Classification 2019 CBC Expansion Classification
0 – 20 Very Low Non-Expansive
21 – 50 Low
Expansive 51 – 90 Medium
91 – 130 High
Greater Than 130 Very High
Geocon Project No. G2225-52-03 - 5 - July 27, 2021
2.2 We performed laboratory tests on samples of the site materials to evaluate the percentage of
water-soluble sulfate content. Results from the laboratory water-soluble sulfate content tests
indicate that the on-site materials at the locations tested possess “S0” sulfate exposure to
concrete structures as defined by 2019 CBC Section 1904 and ACI 318-14, Chapter 19.
2.3 Geocon Incorporated does not practice in the field of corrosion engineering. Therefore,
further evaluation by a corrosion engineer may be performed if improvements susceptible to
corrosion are planned.
3.0 Seismic Design Criteria – 2016 California Building Code
3.1 We used the computer program U.S. Seismic Design Maps, provided by the USGS.
Table 3.1.1 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 site is classified as
a Site Class C in accordance with the 2016 CBC Section 1613. The values presented in
Table 3.1.1 are for the risk-targeted maximum considered earthquake (MCER).
TABLE 3.1.1 2016 CBC SEISMIC DESIGN PARAMETERS
Parameter Value 2016 CBC Reference
Site Class C Section 1613.3.2
MCER Ground Motion Spectral Response Acceleration – Class B (short), SS 1.131g Figure 1613.3.1(1)
MCER Ground Motion Spectral Response
Acceleration – Class B (1 sec), S1 0.434g Figure 1613.3.1(2)
Site Coefficient, FA 1.000 Table 1613.3.3(1)
Site Coefficient, FV 1.366 Table 1613.3.3(2)
Site Class Modified MCERSpectral Response Acceleration (short), SMS 1.131g Section 1613.3.3 (Eqn 16-37)
Site Class Modified MCERSpectral Response Acceleration (1 sec), SM1 0.593g Section 1613.3.3 (Eqn 16-38)
5% Damped Design Spectral Response Acceleration (short), SDS 0.754g Section 1613.3.4 (Eqn 16-39)
5% Damped Design Spectral Response Acceleration (1 sec), SD1 0.395g Section 1613.3.4 (Eqn 16-40)
3.2 Table 3.1.2 presents additional seismic design parameters for projects located in Seismic
Design Categories of D through F in accordance with ASCE 7-10 for the mapped maximum
considered geometric mean (MCEG).
Geocon Project No. G2225-52-03 - 6 - July 27, 2021
TABLE 3.1.2 2016 CBC SITE ACCELERATION DESIGN PARAMETERS
Parameter Value ASCE 7-10 Reference
Mapped MCEG Peak Ground Acceleration, PGA 0.444 Figure 22-7
Site Coefficient, FPGA 1.000 Table 11.8-1
Site Class Modified MCEGPeak Ground Acceleration, PGAM 0.444 Section 11.8.3 (Eqn 11.8-1)
3.3 Conformance to the criteria in Tables 3.1.1 and 3.1.2 for seismic design does not constitute
any kind of guarantee or assurance that significant structural damage or ground failure will
not occur if a 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.
3.4 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 Rick Category of I, II or III and resulting in a Seismic Design Category D.
4.0 Shallow Foundations
4.1 The proposed structures (i.e. shade structures, gazebos) can be supported on a shallow
foundation system founded in compacted fill or Old Paralic Deposits. Foundations for
structures should consist of continuous strip footings and/or isolated spread footings.
Continuous footings should be at least 12 inches wide and extend at least 18 inches below
lowest adjacent pad grade. Isolated spread footings should have a minimum width of 2 feet
and should also extend at least 18 inches below lowest adjacent pad grade. Steel
reinforcement for continuous footings should consist of at least four No. 4 steel reinforcing
bars placed horizontally in the footings, two near the top and two near the bottom. Steel
reinforcement for the spread footings should be designed by the project structural engineer.
In addition, 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.
4.2 The recommendations presented herein are based on soil characteristics only (EI of 50 or
less) and is not intended to replace reinforcement required for structural considerations.
4.3 The recommended allowable bearing capacity for foundations with minimum dimensions
described herein is 2,000 pounds per square foot (psf) for foundations bearing in properly
compacted fill and 4,000 pounds per square foot (psf) for foundations bearing in the Old
Paralic Deposits. The allowable soil bearing pressure may be increased by an additional 500
psf for each additional foot of depth and width, to a maximum allowable bearing capacity of
4,000 psf and 6,000 psf for foundations bearing in compacted fill and Old Paralic Deposits,
Geocon Project No. G2225-52-03 - 7 - July 27, 2021
respectively. The 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.
4.4 We estimate the total and differential settlements under the imposed allowable loads to be
about ½ inch based on a 6-foot square footing.
4.5 Foundation excavations should be observed by the geotechnical engineer (a representative
of Geocon Incorporated) prior to the placement of reinforcing steel to check that the
exposed soil conditions are similar to those expected and that they have been extended to
the appropriate bearing strata. If unexpected soil conditions are encountered, foundation
modifications may be required.
5.0 Drilled Piers
5.1 A deep foundation system consisting of drilled piers may be used to support proposed shade
or light weight structures. The drilled piers can be founded in the properly compacted
structural fill or in the Old Paralic Deposits.
5.2 Drilled piers for the shade structures should be a minimum of 18 inches in diameter and
should be embedded a minimum of 5 feet below the ground surface. In addition, footings
should be deepened such that the bottom outside edge of the footing is at least 7 feet
horizontally from the face of slopes.
5.3 Piers should have a minimum center-to-center spacing of at least three pile diameters.
Drilled piers can be designed to develop support by end bearing and skin friction within the
existing materials. Axial compression capacity may be designed using an allowable skin
friction resistance of 200 psf and 300 psf can be used for that portion of the drilled pier
embedded in fill soil and the Old Paralic Deposits, respectively. Uplift capacity may be
assumed to be 75 percent of the axial capacity in compression. The allowable downward
capacity and allowable uplift capacity may be increased by one-third when considering
transient wind or seismic loads. Where not protected by pavement, the upper 12 inches of
soil should be ignored when calculating axial capacity.
5.4 Piles bearing in compacted fill material may be designed for an allowable bearing capacity
of 2,000 psf. Piles bearing in Old Paralic Deposits may be designed for an allowable bearing
capacity of 4,000 psf.
5.5 We expect the maximum expected total and differential settlement for shade structures
supported on piers deriving support in the compacted fill is about ½ inch. Settlement of the
foundation system is expected to occur on initial application of loading.
Geocon Project No. G2225-52-03 - 8 - July 27, 2021
5.6 Because a significant portion of the pier capacity will be developed by end bearing, the
bottom of the borehole should be cleaned of all loose cuttings prior to the placement of steel
and concrete. Experience indicates that backspinning the auger does not remove loose
material and a flat cleanout plate or hand cleaning is necessary. Concrete should be placed
within the pier excavation as soon as possible after the auger/cleanout plate is withdrawn to
reduce the potential for discontinuities or caving. Pier sidewall instability may randomly
occur if cohesionless soils are encountered. We do not expect seepage will be encountered
during the drilling operations. However, casing may be required to maintain the integrity of
the pier excavation, particularly if seepage or sidewall instability is encountered. The fill
and the formational materials contain gravel, cobble and some boulders. The formational
materials may possess very dense and cemented zones, and difficult drilling conditions
during excavations for the piers should be anticipated.
6.0 Concrete Slabs-On-Grade
6.1 Concrete slabs should possess a thickness of at least 5 inches and reinforced with a
minimum of No. 4 steel reinforcing bars at 18 inches on center in both horizontal directions.
The structural engineer should design the steel required for the planned loading conditions.
The reinforcing steel should be placed in the upper third of the slab with a minimum of 2
inches of cover. Proper positioning of the reinforcement is critical to future performance of
the slab. The contractor should take extra measures to provide proper steel placement. The
concrete should have a compressive strength of at least 3,000 psi.
6.2 If possible, crack-control joints (weakened plane joints) should be included in the design of
the concrete pavement slab to control the location and spread of concrete shrinkage cracks.
Crack-control joints should not exceed 30 times the slab thickness with a maximum spacing
of 12.5 feet for the 5-inch-thick slabs and should be sealed with an appropriate sealant to
prevent the migration of water through the control joint to the subgrade materials. The depth
of the crack-control joints should be determined by the referenced ACI report discussed in
the pavement section herein. Cuts at least ¼ inch wide are required for sealed joints, and a ⅜
inch wide cut is commonly recommended. Coverings on the concrete slab should be
installed in accordance with the manufacturer’s recommendations.
6.3 The slab should be underlain by a minimum of 6 inches of compacted Class 2 Base or
Crushed Aggregate Base (CAB). The slab should be constructed with a thickened edge that
extends at least 12 inches below finish grade and is at least 12 inches wide.
6.4 Prior to the placement of base, the upper 12 inches of soil subgrade should be scarified,
moisture conditioned near to slightly above optimum moisture content, and recompacted to
a dry density of at least 90 percent of the laboratory maximum dry density per ASTM 1557.
Geocon Project No. G2225-52-03 - 9 - July 27, 2021
The base material should also be compacted to a dry density of at least 90 percent of the
laboratory maximum dry density near to slightly above optimum moisture content.
6.5 If the slab will receive a moisture-sensitive covering, a vapor retarder should be placed on the
subgrade below the base as indicated on the attached detail. The vapor retarder 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 accordance with manufacturer’s recommendations
and ASTM requirements and installed in a manner that prevents puncture. The project architect
should specify the type of vapor retarder used based on the type of covering that will be
installed. Class A Stego 15-mil product is typically used for vapor retarders.
6.6 The foundation design engineer should provide appropriate concrete mix design criteria and
curing measures to assure proper curing of the slab by reducing the potential for rapid
moisture loss and subsequent cracking and/or slab curl. We suggest that the foundation
design engineer present the concrete mix design and proper curing methods on the
foundation plans. It is critical that the foundation contractor understands and follows the
recommendations presented on the foundation plans.
6.7 Special subgrade presaturation is not deemed necessary prior to placing concrete; however,
the exposed foundation and slab subgrade soil should be moisturized to maintain a moist
condition as would be expected in any such concrete placement.
7.0 Concrete Flatwork
7.1 Exterior concrete flatwork not subject to vehicular traffic should be constructed in accordance
with the recommendations herein. Slab panels should be a minimum of 4 inches thick and,
when in excess of 8 feet square, should be reinforced with 6 x 6 - W2.9/W2.9 (6 x 6 - 6/6)
welded wire mesh or No. 3 reinforcing bars at 18 inches on center in both directions to reduce
the potential for cracking. Reinforcement is not required where pedestrian walkways are only
4 feet wide. In addition, concrete flatwork should be provided with crack control joints to
reduce and/or control shrinkage cracking. Crack control spacing should be determined by the
project structural engineer based upon the slab thickness and intended usage. Criteria of the
American Concrete Institute (ACI) should be taken into consideration when establishing crack
control spacing. Subgrade soil for exterior slabs not subjected to vehicle loads should be
compacted in accordance with criteria presented in the grading section prior to concrete
placement. Subgrade soil should be properly compacted and the moisture content of subgrade
soil should be checked prior to placing concrete.
7.2 Even with the incorporation of the recommendations within this report, the exterior concrete
flatwork has a likelihood of experiencing some uplift due to expansive soil beneath grade;
Geocon Project No. G2225-52-03 - 10 - July 27, 2021
therefore, the reinforcing steel should overlap continuously in flatwork to reduce the potential
for vertical offsets within flatwork. Additionally, flatwork should be structurally connected to
the curbs, where possible, to reduce the potential for offsets between the curbs and the flatwork.
7.3 Where exterior flatwork abuts the structure at entrant or exit points, the exterior slab should be
dowelled into the structure’s foundation stemwall. This recommendation is intended to reduce
the potential for differential elevations that could result from differential settlement or minor
heave of the flatwork. Dowelling details should be designed by the project structural engineer.
7.4 The recommendations presented herein are intended to reduce the potential for cracking of
slabs and foundations as a result of differential movement. However, even with the
incorporation of the recommendations presented herein, foundations and slabs-on-grade will
still crack. The occurrence of concrete shrinkage cracks is independent of the soil supporting
characteristics. Their occurrence may be reduced and/or controlled by limiting the slump of
the concrete, the use of crack control joints and proper concrete placement and curing.
Literature provided by the Portland Concrete Association (PCA) and American Concrete
Institute (ACI) present recommendations for proper concrete mix, construction, and curing
practices, and should be incorporated into project construction.
8.0 Retaining Walls
8.1 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 density of
35 pounds per cubic foot (pcf). Where the backfill will be inclined at 2:1 (horizontal to
vertical), we recommend an active soil pressure of 50 pcf. Soil with an expansion index (EI)
of greater than 50 should not be used as backfill material behind retaining walls.
8.2 Retaining walls should be designed to ensure stability against overturning sliding, excessive
foundation pressure and water uplift. 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.
8.3 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.
Geocon Project No. G2225-52-03 - 11 - July 27, 2021
8.4 The recommendations presented herein are generally applicable to the design of rigid
concrete. In the event that other types of walls (such as crib-type walls) are planned, Geocon
Incorporated should be consulted for additional recommendations.
8.5 The structural engineer should determine the Seismic Design Category for the project in
accordance with Section 1613.3.5 of the 2016 CBC or Section 11.6 of ASCE 7. 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 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 14H should be used for
design. We used the peak ground acceleration adjusted for Site Class effects, PGAM, of 0.444g
calculated from ASCE 7-10 Section 11.8.3 and applied a pseudo-static coefficient of 0.3.
8.6 The retaining walls may be designed using either the active and restrained (at-rest) loading
condition or the active and seismic loading condition as suggested by the structural
engineer. Typically, it appears the design of the restrained condition for retaining wall
loading may be adequate for the seismic design of the retaining walls. However, the active
earth pressure combined with the seismic design load should be reviewed and also
considered in the design of the retaining walls.
8.7 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 the property adjacent to the base
of the wall. The recommendations herein assume a properly compacted granular (EI of 50 or
less) free-draining backfill material with no hydrostatic forces or imposed surcharge load. If
conditions different than those described are expected, or if specific drainage details are
desired, Geocon Incorporated should be contacted for additional recommendations.
8.8 In general, wall foundations having a minimum depth and width of 1 foot may be designed
for an allowable soil bearing pressure of 2,000 psf. The allowable soil bearing pressure may
be increased by an additional 300 psf for each additional foot of depth and width, to a
maximum allowable bearing capacity of 3,000 psf. 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.
8.9 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
Geocon Project No. G2225-52-03 - 12 - July 27, 2021
should be designed to incorporate an appropriate amount of lateral deflection as determined
by the structural engineer.
8.10 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.
9.0 Lateral Loading
9.1 To resist lateral loads, a passive pressure exerted by an equivalent fluid density of 350 pounds
per cubic foot (pcf) should be used for the design of footings or shear keys. The allowable
passive pressure assumes a horizontal surface extending at least 5 feet, or 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.
9.2 If friction is to be used to resist lateral loads, an allowable coefficient of friction between
soil and concrete of 0.35 should be used for design. The friction coefficient may be reduced
depending on the vapor barrier or waterproofing material used for construction in
accordance with the manufacturer’s recommendations.
9.3 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.
10.0 Site Drainage and Moisture Protection
10.1 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 and improvements. The site should be graded and maintained such that
surface drainage is directed away from structures in accordance with 2016 CBC 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 structure.
10.2 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.
Geocon Project No. G2225-52-03 - 13 - July 27, 2021
NO PARKINGNOPARKING167
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APPROX. LIMITS
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PROPOSED
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6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974
PHONE 858 558-6900 - FAX 858 558-6159 SHEET OF
PROJECT NO.
SCALE DATE
FIGURE
Plotted:07/27/2021 10:03AM | By:JONATHAN WILKINS | File Location:Y:\PROJECTS\G2225-52-03 Buena Vista Reservoir\SHEETS\G2225-52-03 AsGradedMap.dwg
GEOTECHNICAL ENVIRONMENTAL MATERIALS
1" =
AS - GRADED GEOLOGIC 1AP
BUENA VISTA RESERVOIR PARK
CARLSBAD, CALIFORNIA
30' 07 - 27 - 2021
G2225 - 52 - 03
1 1 1
93
167
GEOCON LEGEND
........APPROX. LOCATION OF IN-PLACE DENSITY TEST
........COMPACTED FILLQcf
........OLD PARALIC DEPOSITS (Dotted Where Buried)Qop
........APPROX. ELEVATION AT BOTTOM OF OVEREXCAVATION
(In Feet, MSL)
........APPROX. AREA WHERE CONCRETE LEFT IN PLACE
........UNDOCUMENTED FILLQudf
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GEOS;9~ I NCORPO
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60' 30' 4)
SCALE 1" 30' {On 36x2
90' 120'
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Project Name:Project No.:
Pre. No. Re.
1 01/07/21 Southeast Slope 175 2 0 135.4 7.9 121.2 10.4 90 90
2 01/07/21 Southeast Slope 175 2 0 135.4 7.9 123.2 9.3 91 90
3 01/07/21 Southeast Slope 175 2 0 135.4 7.9 124.9 9.6 92 90
4 01/07/21 Southern Area of Previous Basin 176 1 0 132.1 9.3 118.7 10.3 90 90
5 01/07/21 East-Central PreviousBasin 176 1 0 132.1 9.3 119.6 11.4 91 90
6 01/07/21 Southern Area of Previous Basin 176 1 0 132.1 9.3 118.5 10.6 90 90
7 01/07/21 East-central Previous Basin 176 1 0 132.1 9.3 120.4 10.2 91 90
8 01/07/21 Central Area of PreviousBasin 177 1 0 132.1 9.3 118.3 10.7 90 90
9 01/08/21 Southern Area of PreviousBasin 177 2 0 135.4 7.9 122.2 9.7 90 90
10 01/08/21 Southeast Slope 176 2 0 135.4 7.9 123.5 9.3 91 90
11 01/08/21 Southeast Slope 176 2 0 135.4 7.9 122.8 10.2 91 90
12 01/08/21 Southeast Slope 176 2 0 135.4 7.9 123.6 9.6 91 90
13 01/12/21 Northerrn Area of Previous Basin 178 1 0 132.1 9.3 123.4 10.8 93 90
14 01/12/21 Northerrn Area of Previous Basin 178 1 0 132.1 9.3 119.7 11.3 91 90
15 01/12/21 Central Area of Previous Basin 178 1 0 132.1 9.3 119.0 10.7 90 90
16 01/12/21 Central Area of Previous Basin 178 1 0 132.1 9.3 120.1 10.3 91 90
17 01/12/21 Southern Area of Previous Basin 178 1 0 132.1 9.3 120.5 11.0 91 90
18 01/12/21 Southern Area of Previous Basin 178 1 0 132.1 9.3 119.5 10.5 90 90
19 01/12/21 Northern Area of Previous Basin 179 1 0 132.1 9.3 120.9 10.6 92 90
20 01/12/21 Southern Area of Previous Basin 178 1 0 132.1 9.3 121.2 10.4 92 90
21 01/13/21 Central Area of Previous Basin 178 3 0 129.0 9.7 124.7 8.7 97 90
22 01/13/21 Central Area of Previous Basin 180 3 0 129.0 9.7 123.6 8.9 96 90
23 01/13/21 Southern Area of Previous Basin 180 3 0 129.0 9.7 122.9 8.8 95 90
24 01/13/21 Southern Area of Previous Basin 180 3 0 129.0 9.7 124.8 8.7 97 90
25 01/13/21 Northern Area of Previous Basin 180 3 0 129.0 9.7 124.9 9.3 97 90
26 01/13/21 Northern Area of Previous Basin 180 3 0 129.0 9.7 123.1 8.7 95 90
27 01/14/21 Northern Area of Previous Basin 181 3 0 129.0 9.7 122.7 8.8 95 90
28 01/14/21 Northern Area of Previous Basin 181 3 0 129.0 9.7 122.6 8.7 95 90
29 01/14/21 Central Area of Previous Basin 181 3 0 129.0 9.7 124.6 8.7 97 90
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Buena Vista Reservoir Park G2225-52-03
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/
YY)
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
(%)
0GEOCON
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Buena Vista Reservoir Park G2225-52-03
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/
YY)
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
(%)
30 01/14/21 Central Area of Previous Basin 181 3 0 129.0 9.7 123.2 9.0 96 90
31 01/14/21 Southern Area of Previous Basin 181 3 0 129.0 9.7 123.4 9.1 96 90
32 01/14/21 Southern Area of Previous Basin 181 3 0 129.0 9.7 122.8 8.7 95 90
33 01/14/21 Eastern Slope 177 3 0 129.0 9.7 125.8 8.7 98 90
34 01/14/21 Eastern Slope 177 3 0 129.0 9.7 125.7 8.7 97 90
35 01/15/21 Eastern Slope 178 2 0 135.4 7.9 122.5 7.8 90 90
36 01/15/21 Eastern Slope 178 2 0 135.4 7.9 123.7 7.9 91 90
37 01/19/21 Southwest Slope 175 3 0 129.0 9.7 122.8 9.1 95 90
38 01/19/21 Southwest 177 3 0 129.0 9.7 123.4 9.8 96 90
39 01/19/21 Eastern Slope 179 3 0 129.0 9.7 123.3 10.6 96 90
40 01/19/21 Eastern Slope 181 3 0 129.0 9.7 123.7 9.8 96 90
41 01/19/21 Eastern Slope 183 3 0 129.0 9.7 124.7 9.6 97 90
42 01/19/21 Eastern Slope 182 3 0 129.0 9.7 122.9 9.7 95 90
43 01/19/21 Western Slope 175 3 0 129.0 9.7 122.7 9.9 95 90
44 01/19/21 Western Slope 177 3 0 129.0 9.7 121.3 8.7 94 90
45 01/20/21 Southwest Slope 177 2 0 135.4 7.9 124.8 8.8 92 90
46 01/20/21 Western Side 173 2 0 135.4 7.9 123.8 8.7 91 90
47 01/20/21 Western Side 174 2 0 135.4 7.9 124.7 9.7 92 90
48 01/20/21 Western Side 175 2 0 135.4 7.9 125.9 10.3 93 90
49 01/20/21 Western Side 173 2 0 135.4 7.9 124.6 9.6 92 90
50 01/20/21 Western Side 175 2 0 135.4 7.9 124.3 9.5 92 90
51 01/20/21 Western Side 175 2 0 135.4 7.9 122.9 9.8 91 90
52 01/20/21 Western Side 176 2 0 135.4 7.9 123.3 10.3 91 90
53 01/21/21 Northwet area of site 174 3 0 129.0 9.7 124.4 10.3 96 90
54 01/21/21 West Side 172 3 0 129.0 9.7 123.7 10.6 96 90
55 01/21/21 West Side 168 3 0 129.0 9.7 124.9 9.6 97 90
56 01/21/21 West Side 172 3 0 129.0 9.7 123.6 9.5 96 90
57 01/21/21 Eastern Slope 172 3 0 129.0 9.7 123.3 9.4 96 90
0GEOCON
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Buena Vista Reservoir Park G2225-52-03
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/
YY)
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
(%)
58 01/21/21 Northwest Corner 169 2 0 135.4 7.9 124.9 8.3 92 90
59 01/21/21 Northwest Corner 168 2 0 135.4 7.9 125.0 8.6 92 90
60 01/21/21 Northwest Corner 170 2 0 135.4 7.9 125.1 8.7 92 90
61 01/22/21 Western Side 170 3 0 129.0 9.7 122.2 8.7 95 90
62 01/22/21 Western Side 169 3 0 129.0 9.7 122.8 8.7 95 90
63 01/22/21 Western Side 169 3 0 129.0 9.7 122.7 8.7 95 90
64 01/22/21 Western Side 174 3 0 129.0 9.7 123.4 8.7 96 90
65 01/22/21 Western Side 176 3 0 129.0 9.7 123.6 8.7 96 90
66 01/22/21 Western Side 176 3 0 129.0 9.7 123.2 8.9 96 90
67 01/22/21 Western Side 174 3 0 129.0 9.7 122.8 9.3 95 90
68 01/26/21 Southwest 187 2 0 135.4 7.9 123.4 11.3 91 90
69 01/26/21 Southwest 179 2 0 135.4 7.9 122.7 11.7 91 90
70 R 01/27/21 Western Side 177 3 0 129.0 9.7 118.6 8.8 92 90
71 R 01/27/21 Western Side 176 3 0 129.0 9.7 118.9 8.7 92 90
72 R 01/27/21 Western Side 175 3 0 129.0 9.7 119.6 8.8 93 90
73 R 01/27/21 Western Side 175 3 0 129.0 9.7 120.4 8.9 93 90
74 R 01/27/21 Western Side 176 3 0 129.0 9.7 118.5 8.7 92 90
75 01/27/21 Western Side 177 3 0 129.0 9.7 122.3 8.7 95 90
76 01/27/21 Western Side 176 3 0 129.0 9.7 123.2 8.7 96 90
77 01/27/21 Western Side 175 3 0 129.0 9.7 122.8 8.7 95 90
78 01/27/21 Western Side 176 3 0 129.0 9.7 124.4 8.9 96 90
79 01/27/21 Western Side 175 3 0 129.0 9.7 123.2 9.2 96 90
80 01/28/21 Northwest Area of Site 177 3 0 129.0 9.7 124.6 9.5 97 90
81 01/28/21 Northwest Area of Site 178 3 0 129.0 9.7 123.2 9.2 96 90
82 01/28/21 Northwest Area of Site 174 3 0 129.0 9.7 122.8 9.8 95 90
83 03/16/21 Northern Area of Site 176 3 0 129.0 9.7 122.8 9.8 95 90
84 03/16/21 Northern Area of Site 177 3 0 129.0 9.7 120.7 8.8 94 90
85 03/16/21 Northern Area of Site 179 3 0 129.0 9.7 122.4 8.8 95 90
0GEOCON
- - -
- - -
- - -
- - -
- - -
Project Name:Project No.:
Pre. No. Re.
TABLE I
SUMMARY OF FIELD DENSITY TEST RESULTS
Buena Vista Reservoir Park G2225-52-03
Required
Relative
Compaction
(%)
Test No. Date
(MM/DD/
YY)
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
(%)
86 03/17/21 Northern Area of Site 182 2 0 135.4 7.9 124.8 8.8 92 90
87 03/17/21 Northern Area of Site 181 3 0 129.0 9.7 122.4 8.8 95 90
88 03/18/21 Northwest Area of Site 173 2 0 135.4 7.9 122 8.1 90 90
89 03/18/21 Northwest Area of Site 175 2 0 135.4 7.9 123.6 8.3 91 90
90 6/23/2021 North area of site 181 6 0 131.9 8.3 122.4 7.8 93 90
91 6/23/2021 North area of site 181 6 0 131.9 8.3 120.2 8.8 91 90
92 6/24/2021 North area of site 182 6 0 131.9 8.3 121.6 9.2 92 90
93 6/24/2021 North area of site 178 6 0 131.9 8.3 119.2 9.9 90 90
0GEOCON
Project Name:Buena Vista Reservoir Park Project No.: G2225-52-03
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
0GEOCON
Geocon Project No. G2225-52-03 July 27, 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 wt.)
1 Brown to dark brown, Silty, fine SAND; some gravel (on-site) 132.1 9.3
2 Reddish brown, Silty, fine SAND; trace gravel (on-site) 135.4 7.9
3 Reddish brown, Silty, fine SAND (on-site) 129.0 9.7
6 Olive brown, Silty, fine to coarse SAND (import) 131.9 8.3
TABLE III SUMMARY OF LABORATORY EXPANSION INDEX TEST RESULTS ASTM D 4829
Sample
No.
Moisture Content
(%) Dry
Density
(pcf)
Expansion
Index
ASTM D 4829
Expansion
Classification
2016 CBC Expansion
Classification Before
Test
After
Test
1 8.0 14.4 115.5 0 Very Low Non-Expansive
6 8.8 16.3 114.8 6 Very Low Non-Expansive
TABLE IV
SUMMARY OF WATER-SOLUBLE SULFATE LABORATORY TEST RESULTS CALIFORNIA TEST NO. 417
Sample No. Water Soluble Sulfate (%) ACI 318 Sulfate Exposure
1 0.001 S0
6 0.028 S0