HomeMy WebLinkAboutAsGradedRoughGradingPark(Sept.10,2003)'.
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AS-GRADED REPORT OF ROUGH GRADING
FOR THE HARVESTON COMMUNITY PARK SITE
LOT 9, TRACT 29639-2
CITY OF TEMECULA, CALIFORNIA
Prepared For:
Lennar Comrn~enities
391 N. Main Street, Suite 301
Corona, California 92880
September 10, 2003
Project No. 110231-024
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~eighton and ~~~oci~te~, Inc. =
A LEIGHTON GROUP COMPAPdY
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, Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY
September 10, 2003
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' To: Lennaz Communities
391 N. Main Street, Suite 301
Corona, California 92880
~ Attention: Mr. Bill Storm
Project No. 110231-024
, Subject: As-Graded Report of Rough Grading for the Harveston Community Park Site, Lot 9,
Tract 29639-2, City of Temecula, Califomia.
II , In accordance with your request and authorization, Leighton and Associates, Inc. (Leighton) has been
providing geotechnical observarion and testing services during rough grading operations of Tract
I' 29639-2, located in the City of Temecula, Califomia (See Figure 1). The accompanying as-graded
report summarizes our observations, fieid and laboratory test results and the geotechnical conditions
encountered during the mugh grading of the Aarveston Community Pazk Site, Lot 9 of Tract 29639-2.
, If you have any questions regarding this report, please do not hesitate to contact this office, we
appreciate trris opporttmity to be of service.
' Respectfully submitted,
t LEIGHTON AND ASSOCIATES, INC.
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Robert F. Riha, CEG 1921 (Exp.
Vice President/Principal Geoloa:
RFR/CER/mm
] 10231-024/finaVas-gd rpt hact 29639-2
Cameron Roberson, RCE
Project Engineer
Distribufion: (1) Addressee
(6) Lennaz Communities; Attenfion: Mr. Bob Ha11
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41715 Enterprise Circle N., Suite 103 ^ Temecula, CA 92590-5661
909.296.0530 ^ Fax 909.296.0534 ^ www.leightongeo.com
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September 10, 2003
TABLE OF CONTENTS
Paae
1.0 INTRODUCTION ...............................................................................................................1
2.0 SUMMARY OF ROUGH-GRADING OPERATIONS ...................................................................2
2.1 Site Preparation and Removals ........................................................................ 2
2.2 .........
Field Density Testin9 ................................................................................................ ...
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2.3 Laboratory Testin9 .........................................................................................
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2.4 .
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Fill Placement .................................................................................................... ...3
2.5 ......
Canyon Subdrains .................................................................................................... ...
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' 3.0 ENGINEERING GEOLOGIC SUMMARY .................................................................................4
, 3.1 As-Graded Geologic Conditions ....................................................................................4
3.2 Geologic Units ............................................................................................................4
3.2.1 Aitificial FII ~A~ ...................................................................................................4
' 3.2.2 Artificial FlII Leighton (Afl) ....................................................................................4
3.2.3 Pauba Formation ~QP) .........................................................................................4
' 3.3 Geologic Structure and Faulting ,,,,,,,,,,,,,,,,
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3.4 Landslides and Surficial Failures ...................................................................................5
3.5 Groundwater ..............................................................................................................5
3.6 Expansion Testing of Fnish Grade Soils,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,5
I 4.0 CONCLUSIONS ,,,,,,,,,,,,,,
................... ......... ......... ......... ......... .................6
' 4.1 General..... ...................................................... .........................6
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4.2 Summary of Conclusions .............................................................................................6
, 5.0 RECOMMENDATIONS ........................................................................................................8
5.1 Earthwork ..................................................................................................................$
, 5.1.1 Excavations .......................................................................................................$
5.1.2 Backfill, FII Placement and Compaction ................................................................8
' S.2 Foundation and Structure Design Considerations 8
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5.3 Foundation Setback from Slopes ................................................:...............................10
5.4 Structure Seismic Design Parameters ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,10
, 5.5 Corrosion .................................... ......... ......... ........ ...10
5.6 Lateral Earth Pressures and Retaining Wall Design Considerations ,,,,,,,,, ,,,,,,,,,,,,,,,11
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5.7 Concrete Flatwork ................................................................................................
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5.8 Control of Surface Water and Drainage Control 12
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' S.9 Graded Slopes ..........................................................................................................12
5.10 Irrigation, Landscaping and Lot Maintenance ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,;,,,,,,,,,,,,,,,,,,,,13
5.11 Post-Grading Geotechnical Review ,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,13
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' Table of Contents (cont.)
5.11.1 Construction Review .. 13
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5.11.2 Plans and Specifications ................................................................. .................
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6.0 LIMITATIONS 14
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ccompany
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gures,
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ates and Ap~endices
, Fi ures
Fgure 1- Site Location Map Rear of Text
' Figure 2- Retaining Wall Drainage Detail Rear of Text
' Tables
' Table 1- Minimum Conventional Foundation Design Recommendations
Table 2- Lateral Earth Pressures Rear of Text
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Plate
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I Piate 1- As-Graded Geotechnical Map In Pocket
, Anoendices
Appendix A - References
' Appendix B- Summary of Field Density Tests
Appendix C- Laboratory Testing Procedures and Test Results
Appendix D- Lot Maintenance Guidelines for Owners
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' 1.0 INTRODUCTION
' In acwrdance with your request and authorizarion, Leighton and Associates, Inc. (I,eighton) has
performed geotechnical observation and testing services during the latest rough-grading operations
of the Harveston Community Pazk located within L.ot 9 of Tract 29639-2. The subject property had
' been previously "sheeY' mass graded under the observation and testing of Leighton (Leighton and
Associates, 2003).
' This as-graded report summarizes our geotechnical observations, field and laboratory test results
and the geotechnical conditions encountered during the recent rough grading of the subject lot.
, In addition, this report provides conclusions and recommendations for the proposed development
of the subject lot.
, The reference 50-scale grading plans for I.ot 9, Tract 29639-2 (RBF, 2003) were annotated and
utilized as base maps to plot geotechnical conditions and the approximate locations of the field
density tests taken during rough-gading operations. The locations of the Community Building
' (Building A) and the Restrooms and Community Building (Building B) were overexcavated based
on precise grading plans prepared by RBF Consulting, dated July 25, 2003.
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' 2.0 SUMMARY OF ROUGH-GRADING OPERATIONS
', The Community Park Site along with Tract 29639-1 was nutially sheet graded under the observation
' and tesring of Leighton (Leighton and Associates, 2003). Rough grading to the approved design
configuration (RBF, 2003) was conducted by ACI, Inc. in Mazch through August of 2003, under the
geotechnical observation and testing services of Leighton. Leighton field technician(s) and geologist
' were onsite on a full-time and as-needed basis, respectively, during grading operations. Grading
involved the complete removal of desiccated fill and weathered bedrock to competent previously-
placed compacted fill (I.eighton and Associates, 2003) or bedrock material, and the placement of
' compacted artificial fill to depths of appmximately 19 feet to create the existing Community Pazk Site
and associated roadways.
' 2.1 Site Preparation and Removals
Prior to grading, deleterious materials were removed from the azeas of proposed development
' and disposed of offsite. Grading of the subject site was accomplished by removal of unsuitable
surficial material. The removals were completed until competent previously-placed
compacted fill (Leighton and Associates, 2003) or bedrock material was encountered in
' accordance with the recommendations of the project geotechnical reports (Appendix A) and the
geotechnical recommendations made during grading operations. The two building pads were
over-excavated approximately 3 feet below proposed pad grade elevation (RBF, 2003b) and 5
, feet beyond building perimeter. Building locations were field surveyed by RBF Consulting.
Approximate overexcavation lnnits and bottom elevations are depicted on the enclosed As-
Graded Geotechnical Map (Plate 1).
' 2.2 Field Densitv Testing
' Field density testing was performed using the nuclear gauge method (ASTM Test Methods
D2922 and D3017). Tested azeas appear to meet the minimum required 90 percent relative
' compaction with optimum moishue content or above. Areas that tested less than the required 90
percent relative compac6on, were reworked, moisture conditioned as necessary and compacted
until the minimum 90 percent was obtained. The results and approximate locations of the field
' density tests aze summarized in Appendix B. The approximate locations of the field density tests
are depicted on the enclosed As-Graded Geotechnical Map (Plate 1).
' 2.3 Laboretorv Testing
Laboratory compaction chazacteristics (maximum dry density, and optimum moisture),
' expansion index, Atterberg limits, and soluble sulfate tests of representative onsite soils were
performed during the course of rough-grading. The laboratory test results are presented in
' Table 1 and Appendix C. A description of the laboratory test procedures is presented in
Appendix C.
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' 2.4 Fill Placement
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' Fill consisting of the soil types listed in Appendix C was placed in thin lifts of approximately
eight inches, processed and moisture condifioned to neaz optimum moisture content or above,
' and compacted in place to a minimum of 90 percent of the laboratory derived maximum
density. Fill placement and compaction was accomplished with the use of heavy earthwork
equipment.
' 2.5 Canyon Subdrains
' The existing canyon subdrain constructed during rough-grading of Tract 29639-1 (Leighton and
Associates, 2003) was connected to the existing storm drain at "Lateral A". The approximate
location of the subdrain is presented on the As-Graded Geotechnical Maps (Plate 1). Canyon
' subdrains, as constructed, were surveyed by RBF.
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~ 3.0 ENGINEERING GEOLOGIC SUMMARV
' 3.1 As-Graded Geologic Conditions
' The as-graded conditions encountered during grading of the subject lot was essentially as
anticipated. A sumntary of the geologic conditions, including geologic units, geologic structure
and faulting is presented below.
' 3.2Geoloaic Units
, The geoloac units observed during grading of the subject ]ots consisted of Artificial Fill (A~,
previously-placed compacted fill (Afl), and the Pauba Formation (Qp), which are discussed
below:
, 3.2.1 Artificial Fill (Afl - Locally derived artificial fill soils generally consisted of olive gray to
olive brown silty sand to locally slightly clayey silty sand. Artificial fill soils were placed
' under the observation and field density testing by Leighton representatives during this
phase of grading. After moisture conditioning and thorough mixing the artificial fill soils
' were placed 'm relatively thin (8-10 inches) lifts and compacted utilizing heauy dury
construction equipment.
, 3.2.2 Artificiai Fill Leighton (/,~l - The artificial fill encountered generaliy consisted of
brown to dark brown, moist, medium dense to dense silty sand. As encountered during
grading, the artificial fill was generally moderately dense neaz the surface, becoming dense
' with depth. The weathered artificial fill materials were scarified to a depth of 6 inches,
moistured conditioned and thoroughly mixed and re-used as compacted fill.
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3.2.3 Pauba Formation (Ool - The late Pleistocene-aged Pauba Formation generally
consists of light brown to olive-brown to medium brown, damp to moist, medium dense
to dense, siltstone, sandstone and silty claystone. Fractures aze locally lined with calcium
cazbonate. The Pauba Formation was moisture conditioned and re-used as compacted fill.
3.3 Geologic Structure and Faulting
Based on our geologic observations during site grading, the Pauba Formation is massive with
localized bedding, which is generally flat lying. No faulting or indications of faulting were
anticipated or observed within or immediately adjacent to the subject lot. No faulting or
indications of active faulting was anticipated nor observed within the subject lot during rough-
grading operations. The nearest "zoned" active fault as discussed in the project supplemental
geotechnical investigation report by Leighton (Leighton and Associates, 2001) is the Temecula
Segment of the Elsinore Fault Zone located approximately 2.6 miles (4.2 km) to the southwest.
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3.4 Landslides and SurFicial Failures
Based on our review of the project geotechnical reports (Appendix A) and our geologic
observations during the course of grading operations, there were no indications of landslides or
other significant surficial failures within the subject lot. It should be noted that unplanted or
unprotected slopes aze subject to erosion and subsequent surficial instabilily.
3.5 Groundwater
Groundwater was not encountered during rough grading. Canyon subdrains were constructed
in general accordance with the project geotechnical reports (Appendix A) and our field
recommendations during the previous grading (Leighton and Associates, 2003). However,
unforeseen conditions may occur after the completion of grading and establishment of site
irrigation and landscaping. Perched groundwater may accumulate at layers of differing
permeability or at bedrock/fill contacts. If these conditions should occur, methods should be
taken to mitigate any resulting seepage. Presently the majority of the subject site drains towazds
the south and any surface runoff will tend to collect at low points until such time that the
proposed design drainage facilities aze consiructed. If water is allowed to pond in these azeas
for any length of time the subgrade in these azeas may become saturated and additional grading
recommendations may be required to mitigate this condition. We recommend that the project
erosion control program be designed and implemented as soon as possible to limit the potential
of erosion damage or adverse effects to compacted-fill.
3.6 Exnansion Testing of Finish Grade Soils
Expansion index testing was performed on representative neaz finish grade soils of the proposed
community building pads. The test results indicate near-finish grade soils have a very low to
medium expansion potential in accordance with Table 18-I-B of the 1997 UBC. Test results of
samples taken during the course of gading indicate that very low to very high expansive soils
exist on site at various depths. Test procedures and results aze presenteci in Appendix C.
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' 4.0
' 4.1 General
' The grading of the subject lot was performed in general accordance with the project geotechnical
reports and geotechnical recommendations made during the course of rough grading. It is our
professional opinion that the Community Pazk lot is suitable for its intended public use provided
, the recommendations included herein and in the project geotechnical reports are incorponted into
the design and construcrion of the public structures and associated improvements.
' 4.2 Summarv of Conclusions
. Geotechnical conditions encountered during rough grading of the subject site were generally
' as anticipated.
. Excavations were made to dense previously-placed compacted fill (Afl) or bedrock (Qp)
' material during the grading for the subject lot.
• Cut and fill slopes within the subject lot range up to approximately 8 and 9 feet in height,
respectively. It is our opinion that the compacted fill slopes as well as cut slopes on the
' subject lot are surficially and grossly stable (under normal imgation/precipitation pattems)
provided the recommendations in the project geotechnical reports and memorandums aze
incorporated into the post-grading, construction and post-construction phases of site
' development. Slopes are inherently subject to erosion. As such, measures should be taken
as soon-as possible to reduce erosion for both short term and long term slope integrity.
~ . Laboratory testing of soils encountered during the course of grading indicates site soils to
possess a very low to very high expansion potential. Some expansive soil related distress to
flatwork should be anticipated.
, . Laboratory testing of near finish grade soils within building footprints indicates materials
which posses a low (Building A) to mediuxn (Building B) expansion potential and have a
negligible concentration of soluble.sulfate. Laboratory test results are contained herein
, Table 1 and Appendix C.
. Testing for minimum resistivity, chloride concentrates, and pH was not conducted during
' the course of rough grading. A licensed conosion engineer should be contacted in regazd to
determining the potential for corrosion if conosion sensitive buried improvements aze to be
installed.
, • The potential for ground-surface rupture on the site due to a seismic event is considered to
be low; however, as in most of southem California, strong ground shaking should be
' anticipated during the life of the structures. The standazd design of structures to meet the
seismic design requirements of the Uniform Building Code (iJBC), Seismic Zone 4 will be
required.
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, • Where tested, fill material placed during grading of the subject lot was placed at a minimum
of 90 percent relative compaction at or above the optimum moisture content. Field testing of
' compaction was performed by the nuclear gauge method (ASTM Test Methods D2922 and
D3017).
, . Foundations should be designed and conshucted in accordance with Leighton's minimum
recommendations herein, the requirements of the City of Temecula and the applicable
sections of the 1997 UBC.
, . Due to the relatively dense nature of the bedrock materials that underlie the subject site, the
competency of compacted fills, as well as the lack of permanent shallow groundwater, the
' potential for liquefaction on the site is considered very low.
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5.0 RECOMMENDATIONS
110231-024
September 10, 2003
' 5.1 Earthwork
, We anticipate that future earthwork at the site will consist of finish grading of the building
pads, foundation installation, trench excavation and backfill, retaining wall backfill,
prepazation of sh-eet subgrade, and placement of aggegate base and asphalt concrete
' pavement. We recommend that any additional earthwork on the site be performed in
accordance with the following recommendations and the City of Temecula grading
requirements.
' S.1.1 Fx~?~a*_~~ns -- temporary excavations with vertical sides, such as utility trenches,
should remain stable to depths of 4 feet or less for the period required to conshuct the
' utility. However, in accordance with OSHA requirements, excavations greater than 4
feet in depth should be shored, or laid-back to inclinations of 1:1 (horizontal to
vertical), if workers are to enter such excavations.
' 5.1.2 Backfil~, Fill Placement and Comoaction -- All backfill or fill soils should be
, brought to optimum moisture conditions and compacted in uniform lifts to at least 90
percent relarive compaction based on the laboratory maximum dry density (ASTM
Test Method D1557). The optimum lift thickness required to produce uniform
, compaction will depend on the type, size and condition of compaction equipment
used. In general, the onsite soils should be placed in lifts not exceeding 8 inches in
compacted thiclrness.
' 5.2 Foundation and Structure Desian Considerations
' It is Leighton's understanding that public usage structures founded on conventional
foundation systems aze proposed. The proposed foundations and slabs should be designed in
accordance with the structural consultants' design, the minimum geotechnical
, recommendations presented herein (tezt, Table 1), the City of Temecula requirements and the
1997 UBC. In utilizing the minimum geotechnical foundation recommendations, the
shuctural consultant should design the foundation system to acceptable deflection criteria.
, Foundation footings may be designed with the following pazameters:
' Allowable Bearing Capacity: 2000 psf at a minimum depth of embedment of 12
inches, plus an additional 250 psf per 6 inches of
additional embedment to a maximum of 4000 psf.
, (per 1997 UBC, capacities may be increased by 1/3 for
short-term loading conditions, i.e., wind; seismic)
' Sliding Coefficient: 0.35
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Settlement Potenfial
Total: '/4Inch
Differential: '/< Inch in 40 Feet
110231-024
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The footing width, depth, reinforcement, slab reinforcement, and the slab-on-grade thickness
should be designed by the structural consultant based on recommendations and soil
chazacteristics indicated herein (Tables 1 and 2), and the most recently adopted edition of the
UBC. The under-slab moisture barrier should consist of 2-inches of sand (S.E. > 30) over 10-
mil visqueen over an additional 2-inches of sand. The recommended vapor barrier should be
sealed at all penetrations and laps. Moisture vapor transmission may be additionally reduced
by use of concrete additives. Moisture vapor barriers may retard but not eliminate moisture
vapor movement from the underlying soils up through the slabs. A slipsheet or equivalent
should be utilized above the concrete slab if crack-sensitive floor coverings (such as ceramic
tiles, etc.) aze to be placed directly on the concrete slab.
Our experience indicates that use of reinforcement in slabs and foundations will generally
reduce the potential for drying and shrinkage cracking. However, some cracking should be
expected as the concrete cures. Minor cracking is considered normal; however, it is often
aggravated by a high water/cement ratio, high concrete temperatures at the time of placement,
small nominal aggregate size and rapid moisture loss due to hot, dry and/or windy weather
conditions during placement and curing. Cracking due to temperature and moisture
fluctuations can also be expected. The use of low slump concrete (not exceeding 4 to 5
inches at the rime of placement) can reduce the potential for shrinkage cracking.
Future owners and owners' association should be made aware of the importance of
' maintaining a constant level of soil moisture. Owners should be made aware of the potential
negative consequences of both excessive watering, as well as allowing soils to become too
dry. Improperly designed, constructed, or maintained planters often pond water and cause
, deep moisture penetration and soil moisture change. Since deep and repeated soil moisture
change can damage the adjacent structure, placement of planters adjacent to foundations or
' other sensitive hardscape, should be discouraged if adequate and proper maintenance can not
be assured. Our recommendations assume a reasonable degree of owner responsibility, if the
owners do not adequately maintain correct irrigation and drainage, some degee of foundation
~ movement should be expected. However, this movement typically does not cause structural
damage, but will cause such things as stucco cracking and dry wall separafion.
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t The slab subgrade soils should be presoaked in accordance with the recommendations
presented in Table 1 prior to placement of the moisture barrier and foundation concrete.
, 5.3 foundation Setback from Siopes
' We recommend a minimum horizontal setback distance from the face of slopes for all
structural footings (retaining and decorative walls, building footings, pools, etc.). This
t distance is measured from the outside bottom edge of the footing horizontally to the slope
face (or to the face of a retaining wall) and should be a minimum of H/2, where H is the slope
height (in feet). The setback should not be less than 5 feet and need not be greater than 10
' feet. Please note that the soils within the structural setback azea possess poor lateral stability
and improvements (such as retaining walls, sidewalks, fences, pavements, etc.) constructed
within this setback azea may be subject to lateral movement and/or differential settlement.
' The potential for distress to such improvements may be mitigated by providing a deepened
footing or a pier and grade-beam foundation system to support the impmvement. The
deepened footing should meet the setback as described above. Modificarions of slope
' inclinations neaz foundations may reduce the setback and should be reviewed by the design
team prior to complerion of design or implementation.
' S.4 Structure Seismic Design Parameters
, Structures should be designed as required by provisions of the Uniform Building Code (LJBC)
for Seismic Zone 4 and state-of-the-art seismic design parameters of the Structural Engineers
Association of Califomia. This site is located with UBC Seismic Zone 4. Seismic design
' pazameters in accordance with the 1997 UBC are presented below. Please refer to the
Supplemental Geotechnical Investigation (I.eighton and Associates, 2001) for additional
information.
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Seismic Source Type = B
Near Source Factor, Na =13
Neaz Source Factor, N~ = 1.6
Soil Profile Type = SD
Horizontal Peak Ground Acceleration = 0.68g
(10% probability of exceedance in 50 years)
5.5 Corrosion
A licensed corrosion engineer should be contacted in order to determine the potential for
corrosion if corrosion sensitive buried improvements are planned.
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5.6 Lateral Earth Pressures and Retainina Wall Design Considerations
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The recommended lateral pressures for very low to low expansive site soil (expansion index
less than 51) and level or sloping backfill are presented on Table 2(rear of text).
Embedded structural walls should be designed for lateral earth pressures exerted on them.
The magnitude of these pressures depends on the amount of deformation that the wall can
yield under load. If the wall can yield enough to mobilize the full shear strength of the soil, it
can be designed for "active" pressure. If the wall cannot yield under the applied load, the
shear strength of the soil cannot be mobilized and the earth pressure will be higher. Such
walls should be designed for "at resY' conditions. If a structure moves towazd the soils, the
resulting resistance developed by the soil is the "passive" resistance.
The equivalent fluid weights of Table 2 assume very low to low expansive, free-draining
conditions. If conditions other than those assumed above are anticipated, equivalent fluid
weights should be provided on a case by case basis by the geotechnical engineer. Surcharge
loading effects from adjacent structures should be evalua[ed by the structural engineer. All
retaining wa11 structures should be provided with appropriate drainage and waterproofing.
The outlet pipe should be sloped to drain to a suitable outlet. Typical wall drainage design is
illustrated in Figure 2.
Lateral passive pressures may be determined using the values provided in Table 2. In
combining the total lateral resistance, the passive pressure or the frictional resistance should
be reduced by 50 percent. Wall footings should be designed in accordance with structural
considerations. The passive resistance value may be increased by one-third when considering
loads of short duration, including wind or seismic loads. The horizontal distance between
foundation elements providing passive resistance should be a minimum of three times the
depth of the elements to allow full development of these passive pressures. The total depth of
retained earth for design of cantilever walls should be the vertical distance below the ground
surface measured at the wall face for stem design or measured at the heel of the footing for
overturning and sliding.
Foundations for retaining walls in competent formational soils or properly compacted fill
' should be embedded at least 18 inches below the ]owest adjacent finish grade. At this depth,
an allowable bearing capacity of 2,250 psf may be utilized. The bearing capacity may be
increased by 250 psf for each additional six inches of embedment to a maximum of 4000 psf.
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Wall backcut excavations less than 5 feet in height can be made neaz vertical. For backcuts
greater than 5 feet in height, the backcut should be flattened to a gradient not steeper than 1:1
(horizontal to vertical). Backfill soils should be compacted to at least 90 percent relative
compaction (based on ASTM Test Method D1557). Backfill should extend horizontally to a
minimum distance equal to one-half the wall height behind the walls. The walls should be
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~ conshucted and backfilled as soon as possible after backcut excavation. Prolonged exposure
of backcut slopes may result in some localized slope instability.
' S.7 Concrete Flatwork
~ The reinforcement of driveways, sidewalks, patios, or other concrete flatwork may reduce the
potential for excessive cracking or differential movement, along with keeping sub-grade soil
' at or above optimum moisture content prior to placing concrete. Some expansive soil related
distress should be anticipated over the lifetime ofthe flatwork.
' S.8 Control of Surface Water and Drainaae Control
Positive drainage of surface water away from struchues is very important. No water should
' be allowed to pond adjacent to buildings. Positive drainage may be accomplished by
providing drainage away from buildings at a gradient of at least 2 percent for a distance of at
least 5 feet, and further maintained by a swale on drainage path at a gradient of at least 1
' percent. Where limited, drainage should be directed away from foundations for a minimum
of 3 feet and into a collector swale or pipe system. Where necessary, drainage paths may be
shortened by use of area drains and collector pipes and/or paved swales. Eave gutters also
' help reduce water infiltration into the subgrade soils if the downspouts are properly connected
to appropriate outlets.
' Planters with open bottoms adjacent to buildings should be avoided, if possible. Planters
should not be designed adjacent to buildings unless provisions for drainage, such as catch
' basins and pipe drains, are made. No ponding of water from any source (including
irrigation) should be permitted onsite as moisture infiltration may increase the potential for
moisture-related distress. Experience has shown that even with these controls for surface
' drainage, a shallow perched ground water or subsurface water condition can and may
develop in areas where no such condition previously existed. This is particululy true
where a substantial increase in surface water infiltration resulting from site irrigation
' occurs. Mitigation of these conditions should be performed under the recommendations of
the geotechnical consultant on a case-by-case basis.
' S.9 Graded Slooes
It is recommended that all slopes be planted with drought-tolerant, ground cover vegetation
' as soon.as practical to protect against erosion by reducing runoff velocity. Deep-rooted
vegetation should also be established to provide resistance to surficial slumping.
Oversteepening of existing slopes should be avoided during fine grading and construction.
, Retaining structures to support graded slopes should be designed with structural
considerations and appropriate soil pazameters provided in Section 5.6.
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' 110231-024
September 10, 2003
' S.10 Irriaation, Landscaping and Lot Maintenance
' Site irrigation should be controlled at all times. We recommend that only the minimum
amount of irrigation necessary to maintain plant vigor be utilized. For irrigation of trees
' and shrubs, a drip imgation system should be considered. We recommend that where
possible, landscaping consist primarily of drought-tolerant vegetation. A landscape
consultant should be contacted for proper plant selection. For large graded slopes adjacent
' to open space areas, we recommend native plant species be utilized and that imgation be
utilized only unril plants are well established. At that time, irrigation could be significantly
reduced.
' Recommendations for the maintenance of slopes and pmperty are included in Appendix D for
your review and distribution to future owners and/or owner's associations.
, 5.11 Post-Grading Geotechnical Review
' S.11.1 Construction Review -- Conshuction observation and testing should be performed
by the geotechnical consultant during future excavations, utility trench backfilling
' and foundation or retaining wall construction at the site. Additionally, foofing
excavations should be observed and moisture determination tests of subgrade soils
should be performed by the geotechnical consultant prior to the pouring of concrete.
' S.11.2 Plans and Specifications - The geotechnical engineer should review foundation
plans to evaluate if the recommendations herein have been incorporated. Foundation
' design plans and specifications should be reviewed by the geotechnical consultant
prior to excavation or installation of residential development.
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6.0 LIMITATIONS
110231-024
September 10, 2003
The presence of our field representative at the site was intended to provide the owner with
professional advice, opinions, and recommendations based on observations of the contractor's
work. Although the observations did not reveal obvious deficiencies or deviations from project
specifications, we do not guarantee the contractor's work, nor do our services relieve the contractor
or his subcontractor's work, nor do our services relieve the contractor or his subcontractors of their
responsibility if defects are subsequently discovered in their work. Our responsibilities did not
include any supervision or direction ofthe actual work procedures ofthe contractor, his personnel,
or subcontractors. The conclusions in this report aze based on test results and observations of the
grading and earthwork procedures used and represent our engineering opinion as to the compliance
of the results with the pmject specifications.
This report was prepazed for Lennaz Communities, based on their needs, directions, and requirements
at the time. This report is not authorized for use by, and is not to be relied upon by any party
except, Lennar Communi6es, with whom Leighton contracted for the work. Use of or reliance on
this report by any other party is at that party's risk. Unauthorized use of or reliance on this
Report constitutes an agreement to defend and indemnify Leighton and Associates from and
against any liability which may arise as a result of such use or reliance, regardless of any fault,
negligence, or strict liability of Leighton and Associates.
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Site Location
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Base Map: The Thomas Guide Digital Edition Inland Empire 2000, Not To Scale
Community Park Site, Project No. .~
Tract 29639-2, $ITE LOCATION »ozs~-oza ~~ 4~
Temecula, California MAP Date
Riverside County, California September 2003 Figure No. 1
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SUBDRAIN OPTIONS AND BACKFILL WHEN NATIVE MATERIAL HAS EXPANSION INDEX OF <50
OPRON 1: PIPE SURRWNDED WIfH
CLASS 2 PERMEA&E MATERIPL
WITH PROPEFt
SURFA~ DRAIIJAGE
SLOPE
OR LEVEL
12"
NATNE
WA7ERPROOftNG
(SEE GENERPL NQTES)
WEEP HOLE
($EE NOTE ~
LEVELOR
SLOPE
' 12" MINIMUM
CU55 2 PERMEABIE
FILTER MAiERIAL
. . . (SEE GRADATION)
4INCH DIAMETER
PERFORATED PIPE
($EE NOTE 3)
OPTION 2: GRAVEL WR4PPED
IN FILTER FABRIC
WITH PfiOPER
SURFACE DRAQJAGE
SLOPE
OR LEVEL
12"
WATFRPROOFING ~r.
(SEE GENERAL NOTES)
W EEP HOLE
(SEE NOTE 5) ~
•..
LEVEI OR
SIDPE
Cla$ 2 Fil~r Pertneable Material G2dation
Per Caltrans Specifications
Sieve S'ize P~cent Paginq
I^ 100
3/4" 90-100
3/g" 40-100
N0.4 ZS-90
No. 8 18-33
No.30 5-15
No.50 ~-~
No.200 0-3
GENERAL NOlES:
°IL1ER FABRIC
(SEE NOTE 4)
12" MINA1UM
4a ~0 l~h 1Nq1 SRE
GMbEL WRAPGED IN RLIER
FABRIC
' Waterproofing should be provided where rtroisture nuisance problem thmugh the wall is undesirable.
* Water proofing of the walls is rrot under purview of the geotechnical engineer
* All drains should have a gradient of 1 percent minimum
'Outlet portion of the subdrain should have a 4-inch diameter solid pipe discharged into a suitable disposal area designed by the projec[
engineer. The subdrain pipe should be accessible for maintenance (rodding)
*Other wbdrain bacl~ill options are subject to the review by the geotechnical engineer and modification of dPSign parameters.
Notes:
1) Sand should have a sand equivalent of 30 or greater and may be densified by water jetting.
2) 1 Cu. ft. per ft. of 1/4- to 1 1/2-inch sim gravel wrapped in filter fabric
3) Pipe type should be ASTM D1527 Acryionitrile BuWdiene Styrene (ABS) SDR35 orA57M D3785 Polyvinyl Chloride plastic (PVC), Schedule
40, Artnco A2000 PVC, w approved equivalent. Pipe should be installed with perforations down. Perforations should be 3/8 inch in
diameter placed at the ends of a 120-degree arc in two rows at 3-inch on center (staggered)
4) Flter fabric should be Mirefi 140NC or apprwed equivalent.
5) Weephole should be 3-inch minimum diameter and provided at 10-foot mawmum intenrals. If e~osure is pertnitted, weepholesshould
be located 12 inches above finished grade. If eacposure is not pertnitted such as for a wall adjacent to a sidewalk/curb, a pipe under the
sidewalk to be discharged through the curb face or equivalent should be prwided. For a basgnent-type wall, a proper subdrain outlet
system should be provided.
6) Retaining wall plans should be reviewed and approved by the geotechnical engineer. '
7) Walls over six feet in height are subject to a special review by the geotxhnical engineer and modifiwtions to the above requiremenis.
_.. . __-.___. . .
RETAINING WALL BACKFILL AND SUBDRAIN DETAIL ,~ ~
FOR WALLS 6 FEET OR LESS IN HEIGHT ~~ ~ ~°l-
WHEN NATIVE MATERIAL HAS IXPANSION INDEX OF <50 T
Figure No. 2
110231-024
SeptemCer 10, 2003
TABLE 1
Minimum Conveational Foundation Design Recommendations
Community Building Community Building
(Building A) and Restrooms
(Building B)
1-Story Footing Depth of 12" 18"
Embedment (Exterior and Interior) (Exterior and Interior)
2-Story Footing Depth of 18" Exterior 18"
Embedment 12" Interior (Exterior and Interior)
Isolated Column Footings Exterior " "
of Minimum Foundarion 18 24
Presoaking 120 % of optimum moisriue content
"
to a d th of 12
No. 3 rebaz placed at No. 3 rebaz placed at
Minimum Slab Reinforcement ~d-slab height spaced mid-slab height spaced
18 inches on center, 15 inches on center,
each way each way
Two inches of sand over a 10-mil polyvinyl
Underslab Treahnent membrane (Visqueen or equivalent) over an
additional two inches of sand.
Notes:
(1) Depth of interior or exterior footing io be measured from lowest adjacent finish grade.
If drainage swale flowline elevation is less than S feet laterally from footing, footing
bottom to be minimum 6 inches below swale flowline.
(2) Underslab treatment sand should have a Sand Equivalent of 30 or greater (e.g. washed
concrete sand).
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September 10, 2003
TABLE 2
Lateral Earth Pressuresl
Equivalent F'luid Weight (pc~
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Level BackfillZ 2:1 Slope Backfill
Acrive 45 67
At-Rest 65 95
Passive3 300 125 (Sloping Down)
tAssumes drained condition (See Figure 1)
zAssumes a level condition behind and in front of wall foundation of project.
3Masimum passive pressure = 4000 psf, level condirions.
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September 10, 2003
' APPENDIX A
' References
' Leighton and Associates, 2001, Supplemental Geotechnical Investigation and Geotechnical
Review of 100-Scale Mass Grading Plan, Tentative Tract No. 29639,
Harveston, Temecula, California, LDOI-058GR, Project No. 110231-003,
' dated August 15, 2001.
Leighton and Associates, 2003, As-Graded Report of Mass Grading Harveston, Tract 29639-1, City
' of Temecula, Califomia, Project No. 110231-006, dated February 5, 2003.
Naval Facili6es Engineering Command, 1986a, Soil mechanics design manual 7.01, Change 1:
~ U.S. Navy, September.
Nava1 Facilities Engineering Command, 1986b, Foundations and earth shuctures, design manual
' 7.02, Changes 1: U.S. Navy, September.
, RBF Consulting, 2003a, Harveston Mass Grading, Tract 29639-Phase 2, July 2003, LD02-
217GR, Sheet 6A of 10.
' RBF Consulting, 2003b, Harveston Tract 29639-2, Lot 9, Precise Grading Plan, 11 Sheets, dated
June 25, 2003.
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110231-024
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Ex~lanation of Summary of Field Densitv Tests
A: Retest of previously failing compaction test.
B: Second retest oFpreviously failing compaction test.
Compaction tests taken during mass grading of site unless indicated by:
FG: Compaction tests taken on rough finish grade.
SF: Compaction tests taken on slope face.
Test Location :Indicated by lot number.
Test Method :Compacrion test by Nucleaz Gage (ASTM 2922) unless indicated by
S: Sand Cone Method (ASTM 1556).
Test Elevation : Approximate elevation above mean sea level.
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110231-024
September 10, 2003
APPENDDCC
Laboratorv Testing Procedures and Test Results
Expansion Index Tests: The expansion potential of selected materials was evaluated by the
Expansion Index Test, ASTM test method D4829 or U.B.C. Standard No. 18-2. Specimens aze
molded under a given compactive energy to approximately the optimum moishue content and
approximately 50 percent saturation or approximately 90 percent relative compaction. The
prepazed 1-inch thick by 4-inch diameter specimens are loaded to an equivalent 144 psf surcharge
and aze inundated with tap water until volumetric equilibrium is reached. The results of these tests
aze presented in the table below and in the compacrion chazacteristics table herewith Appendix C:
Sample Locarion Sample Description Expansion Expansion
Index Potential
Community Building
uildin A
Brown Silty Clayey Sand
46
I.ow
Community and
Restroom Building Olive Brown Lean Silt 62 Medium
uilding B)
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Laboratory lcont'd)
Comroaction Chazacteristics: The maximum dry density and optimum moisture content of typical
materials were determined in accordance with ASTM Test Method D1557. The results of these
tests aze presented in the table below:
Water-
O1 M~~~ Optimum Soluable
T
e Sample Description Dry Density Moisture Sulfate Sulfate Expansion Expansion
YP ~~~ Content (Soa) in *
Exposure Index Potential
(%) Soil, %by
weight
2 Brown silty sand 129.5 9.0 0.015 Negligible 0 Very Low
3 Brown silty sand 115.5 15.5 0.015 Negligible 55 Medium
4 Yellow brown to 121.0 g.s 0.015 Negligible 35 ~W
olive brown silty sand
5 Gray-olive to brown 116.0 12.0 0.015 Negligible 91 High
olive sandy clay
8 Dazk olive brown 128.5 11.0 <0.015 Negligible 54 Medium
sandy lean clay
9 Yellow brown sandy 119.5 10.0 <0.015 Negligible 32 ~W
silt
16 e brown clayey
~ 120.0 12.5 <0.015 Negligible 156 Very High
and
18 D
az
kbrownclayey 132.0 8.0 0.017 Negligible 29 I,ow
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19 S at olive tan silty 127.0 9.5 <0.015 Negligible 17 Very Low
25 Brown silty sand 130.0 10.5 0.015 Negligible 21 Low
2~ RaY brown sand with 126.0 10.5 <0.015 Negligible 48 Low
28 Olive brown silty 122.0 12.0 0.017 Negligible 18 Very Low
sand
29 raa sh brown silty
S 126.0 9.5 <0.015 Negligible 16 V~y ~µ,
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33 S~t brown silty 115.0 15.0 <0.015 Negligible 55 Medium
44 Band silty clayey 126.0 10.5 0.024 Negligible 45 ~µ.
62 sOande silt to clayey 108.0 19.0 N/A N/A N/A N/A
64 Brown silty sand 132.0 9,p <0.015 Negligible 0 Very Low
65 Brown silty sand 132.5 9.0 <0.015 Negligible 42 ~W
67 Brown silty sand 120.0 10.5 <0.015 Negligible 0 Very I.ow
70 Brown sandy lean 127.0 11.0 <0.015 Negligible 56 Medium
° nasea on me tyyi eamon ot me umiorm t3wldmg C;ode, Table No. 19-A-4, prepazed by the
Intemational Conference of Building Officials (ICBO).
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' APPENDIX D
' Lot MaintPnancp ~id lin for O~sn rs
' Development azeas, in general, and hillside lots, in particular, need maintenance to continue to
function and retain their value. Many owners aze unaware of tkus and allow deterioration of the
property. It is ixnportant to fanuliarize owners with some guidelines for maintenance of their
' properties and make them awaze of the importance of maintenance.
Some governing agencies require hillside pmperty developers to utilize specific methods of
' engineering and construction to protect those investing in improved lots or constructed homes. For
example, the developer may be required to grade the property in such a manner that rainwater will
be drained away from the lot and to plant slopes so that erosion will be minimized. They may also
' be required to install permanent drains.
However, once the lot is purchased, it is the buyer's responsibility to maintain these safety features
' by observing a prudent pmgam of lot caze and maintenance. Failure to make regulaz inspection
and maintenance of drainage devices and sloping areas may cause severe financial loss. In addition
' to their own property damage, they may be subject to civil liability for damage occurring to
neighboring properties as a resuit of his negligence.
' The following maintenance guidelines aze provided for the protecrion of the owner's inveshnent.
a) Caze should be taken that slopes, terraces, berms (ridges at crown of slopes) and pmper lot
' drainage aze not disturbed. Surface drainage should be conducted from the reaz yard to the
street through the side yard, or altemative approved devices.
' b) In general, roof and yard runoff should be conducted to either the street or storm drain by
nonerosive devices such as sidewalks, drainage pipes, ground gutters, and driveways.
Drainage systems should not be altered without expert consultation.
' c) All drains should be kept cleaned and unclogged, including gutters and downspouts. Terrace
drains or gunite ditches should be kept free of debris to allow proper drainage. During heavy
' rain periods, performance of the drainage system should be inspected. Problems, such as
gullying and ponding, if observed, should be corrected as soon as possible.
' d) Any leakage from pools, water lines, etc. or bypassing of drains should be repaired as soon as
practical.
' e) Animal burrows should be eliminated since they may cause diversion of surface runoff,
promote accelerated erosion, and even trigger shallow soil flowage.
' ~ Slopes should not be altered without expert consultation. Whenever a significant topographic
modification of the lot or slope, is desired a qualified geotechnical consultant should be
' contacted.
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g) If the owner plans to modify cut or natural slopes are proposed, an engineering geologist
' should be consulted. Any oversteepening may result in a need for expensive retaining devices.
Undercutting of a toe-of-slope would reduce the safety factor of the slope and should not be
undertaken without expert consultation.
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h) If unusual cracldng settling or earth slippage occurs on the pmperty, the owner should consult
a qualified soil engineer or an engineering geologist immediately.
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i) The most common causes of slope erosion and shallow slope failures aze as follows:
' • Gross neglect of the caze and maintenance of the slopes and drainage devices.
• Inadequate and/or impmper planting. (Barren areas should be replanted as soon as
' possible.)
~ • Excessive or insufficient irrigarion or diveision of runoff over the slope.
j) Hillside lot owners should not let condirions on theu property create a pmblem for their
neighbors. Cooperation with neighbors could prevent problems, promote slope stability,
' adequate drainage, pmper maintenance, and also increase the aesthetic attractiveness of the
community.
' k) Ownet's should be aware of the chemical composition of imported soils, soil amendments, and
fertilizers to be utilized for landscaping purposes. Some soils, soil aznendments and fertilizer
' can leach soluble sulfates, increasing soluble sulfate concentrations to moderate or severe
concentrarions, negarively affecting the performance of concrete improvements, including
foundarions and flatwork.
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